diff --git a/content/canvas/src/CanvasUtils.cpp b/content/canvas/src/CanvasUtils.cpp
index 4cfd2c00e9e..983ce906964 100644
--- a/content/canvas/src/CanvasUtils.cpp
+++ b/content/canvas/src/CanvasUtils.cpp
@@ -57,13 +57,15 @@
 #include "nsTArray.h"
 
 #include "CanvasUtils.h"
+#include "mozilla/gfx/Matrix.h"
 
-using namespace mozilla;
+namespace mozilla {
+namespace CanvasUtils {
 
 void
-CanvasUtils::DoDrawImageSecurityCheck(nsHTMLCanvasElement *aCanvasElement,
-                                      nsIPrincipal *aPrincipal,
-                                      PRBool forceWriteOnly)
+DoDrawImageSecurityCheck(nsHTMLCanvasElement *aCanvasElement,
+                         nsIPrincipal *aPrincipal,
+                         PRBool forceWriteOnly)
 {
     // Callers should ensure that mCanvasElement is non-null before calling this
     if (!aCanvasElement) {
@@ -96,7 +98,7 @@ CanvasUtils::DoDrawImageSecurityCheck(nsHTMLCanvasElement *aCanvasElement,
 }
 
 void
-CanvasUtils::LogMessage (const nsCString& errorString)
+LogMessage (const nsCString& errorString)
 {
     nsCOMPtr<nsIConsoleService> console(do_GetService(NS_CONSOLESERVICE_CONTRACTID));
     if (!console)
@@ -107,7 +109,7 @@ CanvasUtils::LogMessage (const nsCString& errorString)
 }
 
 void
-CanvasUtils::LogMessagef (const char *fmt, ...)
+LogMessagef (const char *fmt, ...)
 {
     va_list ap;
     va_start(ap, fmt);
@@ -122,3 +124,115 @@ CanvasUtils::LogMessagef (const char *fmt, ...)
 
     va_end(ap);
 }
+
+bool
+CoerceDouble(jsval v, double* d)
+{
+    if (JSVAL_IS_DOUBLE(v)) {
+        *d = JSVAL_TO_DOUBLE(v);
+    } else if (JSVAL_IS_INT(v)) {
+        *d = double(JSVAL_TO_INT(v));
+    } else if (JSVAL_IS_VOID(v)) {
+        *d = 0.0;
+    } else {
+        return false;
+    }
+    return true;
+}
+
+template<size_t N>
+static bool
+JSValToMatrixElts(JSContext* cx, const jsval& val,
+                  double* (&elts)[N], nsresult* rv)
+{
+    JSObject* obj;
+    jsuint length;
+
+    if (JSVAL_IS_PRIMITIVE(val) ||
+        !(obj = JSVAL_TO_OBJECT(val)) ||
+        !JS_GetArrayLength(cx, obj, &length) ||
+        N != length) {
+        // Not an array-like thing or wrong size
+        *rv = NS_ERROR_INVALID_ARG;
+        return false;
+    }
+
+    for (PRUint32 i = 0; i < N; ++i) {
+        jsval elt;
+        double d;
+        if (!JS_GetElement(cx, obj, i, &elt)) {
+            *rv = NS_ERROR_FAILURE;
+            return false;
+        }
+        if (!CoerceDouble(elt, &d)) {
+            *rv = NS_ERROR_INVALID_ARG;
+            return false;
+        }
+        if (!FloatValidate(d)) {
+            // This is weird, but it's the behavior of SetTransform()
+            *rv = NS_OK;
+            return false;
+        }
+        *elts[i] = d;
+    }
+
+    *rv = NS_OK;
+    return true;
+}
+
+bool
+JSValToMatrix(JSContext* cx, const jsval& val, gfxMatrix* matrix, nsresult* rv)
+{
+    double* elts[] = { &matrix->xx, &matrix->yx, &matrix->xy, &matrix->yy,
+                       &matrix->x0, &matrix->y0 };
+    return JSValToMatrixElts(cx, val, elts, rv);
+}
+
+bool
+JSValToMatrix(JSContext* cx, const jsval& val, Matrix* matrix, nsresult* rv)
+{
+    gfxMatrix m;
+    if (!JSValToMatrix(cx, val, &m, rv))
+        return false;
+    *matrix = Matrix(m.xx, m.yx, m.xy, m.yy, m.x0, m.y0);
+    return true;
+}
+
+template<size_t N>
+static nsresult
+MatrixEltsToJSVal(/*const*/ jsval (&elts)[N], JSContext* cx, jsval* val)
+{
+    JSObject* obj = JS_NewArrayObject(cx, N, elts);
+    if  (!obj) {
+        return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    *val = OBJECT_TO_JSVAL(obj);
+
+    return NS_OK;
+}
+
+nsresult
+MatrixToJSVal(const gfxMatrix& matrix, JSContext* cx, jsval* val)
+{
+    jsval elts[] = {
+        DOUBLE_TO_JSVAL(matrix.xx), DOUBLE_TO_JSVAL(matrix.yx),
+        DOUBLE_TO_JSVAL(matrix.xy), DOUBLE_TO_JSVAL(matrix.yy),
+        DOUBLE_TO_JSVAL(matrix.x0), DOUBLE_TO_JSVAL(matrix.y0)
+    };
+    return MatrixEltsToJSVal(elts, cx, val);
+}
+
+nsresult
+MatrixToJSVal(const Matrix& matrix, JSContext* cx, jsval* val)
+{
+    jsval elts[] = {
+        DOUBLE_TO_JSVAL(matrix._11), DOUBLE_TO_JSVAL(matrix._12),
+        DOUBLE_TO_JSVAL(matrix._21), DOUBLE_TO_JSVAL(matrix._22),
+        DOUBLE_TO_JSVAL(matrix._31), DOUBLE_TO_JSVAL(matrix._32)
+    };
+    return MatrixEltsToJSVal(elts, cx, val);
+}
+
+} // namespace CanvasUtils
+} // namespace mozilla
diff --git a/content/canvas/src/CanvasUtils.h b/content/canvas/src/CanvasUtils.h
index e9087f64379..d1ec418dbcf 100644
--- a/content/canvas/src/CanvasUtils.h
+++ b/content/canvas/src/CanvasUtils.h
@@ -47,37 +47,91 @@ class nsIPrincipal;
 
 namespace mozilla {
 
-class CanvasUtils {
-public:
-    // Check that the rectangle [x,y,w,h] is a subrectangle of [0,0,realWidth,realHeight]
+namespace gfx {
+class Matrix;
+}
 
-    static PRBool CheckSaneSubrectSize(PRInt32 x, PRInt32 y, PRInt32 w, PRInt32 h,
-                                       PRInt32 realWidth, PRInt32 realHeight) {
-        CheckedInt32 checked_x_plus_w  = CheckedInt32(x) + w;
-        CheckedInt32 checked_y_plus_h  = CheckedInt32(y) + h;
+namespace CanvasUtils {
 
-        return w >= 0 && h >= 0 && x >= 0 && y >= 0 &&
-            checked_x_plus_w.valid() &&
-            checked_x_plus_w.value() <= realWidth &&
-            checked_y_plus_h.valid() &&
-            checked_y_plus_h.value() <= realHeight;
-    }
+using namespace gfx;
 
-    // Flag aCanvasElement as write-only if drawing an image with aPrincipal
-    // onto it would make it such.
+// Check that the rectangle [x,y,w,h] is a subrectangle of [0,0,realWidth,realHeight]
 
-    static void DoDrawImageSecurityCheck(nsHTMLCanvasElement *aCanvasElement,
-                                         nsIPrincipal *aPrincipal,
-                                         PRBool forceWriteOnly);
+inline PRBool CheckSaneSubrectSize(PRInt32 x, PRInt32 y, PRInt32 w, PRInt32 h,
+                            PRInt32 realWidth, PRInt32 realHeight) {
+    CheckedInt32 checked_xmost  = CheckedInt32(x) + w;
+    CheckedInt32 checked_ymost  = CheckedInt32(y) + h;
 
-    static void LogMessage (const nsCString& errorString);
-    static void LogMessagef (const char *fmt, ...);
+    return w >= 0 && h >= 0 && x >= 0 && y >= 0 &&
+        checked_xmost.valid() &&
+        checked_xmost.value() <= realWidth &&
+        checked_ymost.valid() &&
+        checked_ymost.value() <= realHeight;
+}
 
-private:
-    // this can't be instantiated
-    CanvasUtils() { }
-};
+// Flag aCanvasElement as write-only if drawing an image with aPrincipal
+// onto it would make it such.
 
+void DoDrawImageSecurityCheck(nsHTMLCanvasElement *aCanvasElement,
+                              nsIPrincipal *aPrincipal,
+                              PRBool forceWriteOnly);
+
+void LogMessage (const nsCString& errorString);
+void LogMessagef (const char *fmt, ...);
+
+// Make a double out of |v|, treating undefined values as 0.0 (for
+// the sake of sparse arrays).  Return true iff coercion
+// succeeded.
+bool CoerceDouble(jsval v, double* d);
+
+// Return true iff the conversion succeeded, false otherwise.  *rv is
+// the value to return to script if this returns false.
+bool JSValToMatrix(JSContext* cx, const jsval& val,
+                   gfxMatrix* matrix, nsresult* rv);
+bool JSValToMatrix(JSContext* cx, const jsval& val,
+                   Matrix* matrix, nsresult* rv);
+
+nsresult MatrixToJSVal(const gfxMatrix& matrix,
+                       JSContext* cx, jsval* val);
+nsresult MatrixToJSVal(const Matrix& matrix,
+                       JSContext* cx, jsval* val);
+
+    /* Float validation stuff */
+#define VALIDATE(_f)  if (!NS_finite(_f)) return PR_FALSE
+
+inline PRBool FloatValidate (double f1) {
+    VALIDATE(f1);
+    return PR_TRUE;
+}
+
+inline PRBool FloatValidate (double f1, double f2) {
+    VALIDATE(f1); VALIDATE(f2);
+    return PR_TRUE;
+}
+
+inline PRBool FloatValidate (double f1, double f2, double f3) {
+    VALIDATE(f1); VALIDATE(f2); VALIDATE(f3);
+    return PR_TRUE;
+}
+
+inline PRBool FloatValidate (double f1, double f2, double f3, double f4) {
+    VALIDATE(f1); VALIDATE(f2); VALIDATE(f3); VALIDATE(f4);
+    return PR_TRUE;
+}
+
+inline PRBool FloatValidate (double f1, double f2, double f3, double f4, double f5) {
+    VALIDATE(f1); VALIDATE(f2); VALIDATE(f3); VALIDATE(f4); VALIDATE(f5);
+    return PR_TRUE;
+}
+
+inline PRBool FloatValidate (double f1, double f2, double f3, double f4, double f5, double f6) {
+    VALIDATE(f1); VALIDATE(f2); VALIDATE(f3); VALIDATE(f4); VALIDATE(f5); VALIDATE(f6);
+    return PR_TRUE;
+}
+
+#undef VALIDATE
+
+}
 }
 
 #endif /* _CANVASUTILS_H_ */
diff --git a/content/canvas/src/nsCanvasRenderingContext2D.cpp b/content/canvas/src/nsCanvasRenderingContext2D.cpp
index ab35bb47536..c1552757498 100644
--- a/content/canvas/src/nsCanvasRenderingContext2D.cpp
+++ b/content/canvas/src/nsCanvasRenderingContext2D.cpp
@@ -119,51 +119,16 @@
 // windows.h (included by chromium code) defines this, in its infinite wisdom
 #undef DrawText
 
-using namespace mozilla::ipc;
-
 using namespace mozilla;
-using namespace mozilla::layers;
+using namespace mozilla::CanvasUtils;
 using namespace mozilla::dom;
+using namespace mozilla::ipc;
+using namespace mozilla::layers;
 
 static float kDefaultFontSize = 10.0;
 static NS_NAMED_LITERAL_STRING(kDefaultFontName, "sans-serif");
 static NS_NAMED_LITERAL_STRING(kDefaultFontStyle, "10px sans-serif");
 
-/* Float validation stuff */
-#define VALIDATE(_f)  if (!NS_finite(_f)) return PR_FALSE
-
-static PRBool FloatValidate (double f1) {
-    VALIDATE(f1);
-    return PR_TRUE;
-}
-
-static PRBool FloatValidate (double f1, double f2) {
-    VALIDATE(f1); VALIDATE(f2);
-    return PR_TRUE;
-}
-
-static PRBool FloatValidate (double f1, double f2, double f3) {
-    VALIDATE(f1); VALIDATE(f2); VALIDATE(f3);
-    return PR_TRUE;
-}
-
-static PRBool FloatValidate (double f1, double f2, double f3, double f4) {
-    VALIDATE(f1); VALIDATE(f2); VALIDATE(f3); VALIDATE(f4);
-    return PR_TRUE;
-}
-
-static PRBool FloatValidate (double f1, double f2, double f3, double f4, double f5) {
-    VALIDATE(f1); VALIDATE(f2); VALIDATE(f3); VALIDATE(f4); VALIDATE(f5);
-    return PR_TRUE;
-}
-
-static PRBool FloatValidate (double f1, double f2, double f3, double f4, double f5, double f6) {
-    VALIDATE(f1); VALIDATE(f2); VALIDATE(f3); VALIDATE(f4); VALIDATE(f5); VALIDATE(f6);
-    return PR_TRUE;
-}
-
-#undef VALIDATE
-
 /* Memory reporter stuff */
 static nsIMemoryReporter *gCanvasMemoryReporter = nsnull;
 static PRInt64 gCanvasMemoryUsed = 0;
@@ -1436,6 +1401,64 @@ nsCanvasRenderingContext2D::SetTransform(float m11, float m12, float m21, float
     return NS_OK;
 }
 
+NS_IMETHODIMP
+nsCanvasRenderingContext2D::SetMozCurrentTransform(JSContext* cx,
+                                                   const jsval& matrix)
+{
+    nsresult rv;
+    gfxMatrix newCTM;
+
+    if (!JSValToMatrix(cx, matrix, &newCTM, &rv)) {
+        return rv;
+    }
+
+    mThebes->SetMatrix(newCTM);
+
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+nsCanvasRenderingContext2D::GetMozCurrentTransform(JSContext* cx,
+                                                   jsval* matrix)
+{
+    return MatrixToJSVal(mThebes->CurrentMatrix(), cx, matrix);
+}
+
+NS_IMETHODIMP
+nsCanvasRenderingContext2D::SetMozCurrentTransformInverse(JSContext* cx,
+                                                          const jsval& matrix)
+{
+    nsresult rv;
+    gfxMatrix newCTMInverse;
+
+    if (!JSValToMatrix(cx, matrix, &newCTMInverse, &rv)) {
+        return rv;
+    }
+
+    // XXX ERRMSG we need to report an error to developers here! (bug 329026)
+    if (!newCTMInverse.IsSingular()) {
+        mThebes->SetMatrix(newCTMInverse.Invert());
+    }
+
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+nsCanvasRenderingContext2D::GetMozCurrentTransformInverse(JSContext* cx,
+                                                          jsval* matrix)
+{
+    gfxMatrix ctm = mThebes->CurrentMatrix();
+
+    if (!mThebes->CurrentMatrix().IsSingular()) {
+        ctm.Invert();
+    } else {
+        double NaN = JSVAL_TO_DOUBLE(JS_GetNaNValue(cx));
+        ctm = gfxMatrix(NaN, NaN, NaN, NaN, NaN, NaN);
+    }
+
+    return MatrixToJSVal(ctm, cx, matrix);
+}
+
 //
 // colors
 //
diff --git a/content/canvas/src/nsCanvasRenderingContext2DAzure.cpp b/content/canvas/src/nsCanvasRenderingContext2DAzure.cpp
index f4793d499d6..68333f25981 100644
--- a/content/canvas/src/nsCanvasRenderingContext2DAzure.cpp
+++ b/content/canvas/src/nsCanvasRenderingContext2DAzure.cpp
@@ -127,11 +127,12 @@
 #undef DrawText
 
 using namespace mozilla;
-using namespace mozilla::layers;
+using namespace mozilla::CanvasUtils;
+using namespace mozilla::css;
 using namespace mozilla::dom;
 using namespace mozilla::gfx;
 using namespace mozilla::ipc;
-using namespace mozilla::css;
+using namespace mozilla::layers;
 
 namespace mgfx = mozilla::gfx;
 
@@ -139,41 +140,6 @@ static float kDefaultFontSize = 10.0;
 static NS_NAMED_LITERAL_STRING(kDefaultFontName, "sans-serif");
 static NS_NAMED_LITERAL_STRING(kDefaultFontStyle, "10px sans-serif");
 
-/* Float validation stuff */
-#define VALIDATE(_f)  if (!NS_finite(_f)) return PR_FALSE
-
-static PRBool FloatValidate (double f1) {
-  VALIDATE(f1);
-  return PR_TRUE;
-}
-
-static PRBool FloatValidate (double f1, double f2) {
-  VALIDATE(f1); VALIDATE(f2);
-  return PR_TRUE;
-}
-
-static PRBool FloatValidate (double f1, double f2, double f3) {
-  VALIDATE(f1); VALIDATE(f2); VALIDATE(f3);
-  return PR_TRUE;
-}
-
-static PRBool FloatValidate (double f1, double f2, double f3, double f4) {
-  VALIDATE(f1); VALIDATE(f2); VALIDATE(f3); VALIDATE(f4);
-  return PR_TRUE;
-}
-
-static PRBool FloatValidate (double f1, double f2, double f3, double f4, double f5) {
-  VALIDATE(f1); VALIDATE(f2); VALIDATE(f3); VALIDATE(f4); VALIDATE(f5);
-  return PR_TRUE;
-}
-
-static PRBool FloatValidate (double f1, double f2, double f3, double f4, double f5, double f6) {
-  VALIDATE(f1); VALIDATE(f2); VALIDATE(f3); VALIDATE(f4); VALIDATE(f5); VALIDATE(f6);
-  return PR_TRUE;
-}
-
-#undef VALIDATE
-
 /* Memory reporter stuff */
 static nsIMemoryReporter *gCanvasAzureMemoryReporter = nsnull;
 static PRInt64 gCanvasAzureMemoryUsed = 0;
@@ -1625,6 +1591,62 @@ nsCanvasRenderingContext2DAzure::SetTransform(float m11, float m12, float m21, f
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsCanvasRenderingContext2DAzure::SetMozCurrentTransform(JSContext* cx,
+                                                        const jsval& matrix)
+{
+  nsresult rv;
+  Matrix newCTM;
+
+  if (!JSValToMatrix(cx, matrix, &newCTM, &rv)) {
+    return rv;
+  }
+
+  mTarget->SetTransform(newCTM);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsCanvasRenderingContext2DAzure::GetMozCurrentTransform(JSContext* cx,
+                                                        jsval* matrix)
+{
+  return MatrixToJSVal(mTarget->GetTransform(), cx, matrix);
+}
+
+NS_IMETHODIMP
+nsCanvasRenderingContext2DAzure::SetMozCurrentTransformInverse(JSContext* cx,
+                                                               const jsval& matrix)
+{
+  nsresult rv;
+  Matrix newCTMInverse;
+
+  if (!JSValToMatrix(cx, matrix, &newCTMInverse, &rv)) {
+    return rv;
+  }
+
+  // XXX ERRMSG we need to report an error to developers here! (bug 329026)
+  if (newCTMInverse.Invert()) {
+    mTarget->SetTransform(newCTMInverse);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsCanvasRenderingContext2DAzure::GetMozCurrentTransformInverse(JSContext* cx,
+                                                               jsval* matrix)
+{
+  Matrix ctm = mTarget->GetTransform();
+
+  if (!ctm.Invert()) {
+    double NaN = JSVAL_TO_DOUBLE(JS_GetNaNValue(cx));
+    ctm = Matrix(NaN, NaN, NaN, NaN, NaN, NaN);
+  }
+
+  return MatrixToJSVal(ctm, cx, matrix);
+}
+
 //
 // colors
 //
@@ -2050,8 +2072,6 @@ nsCanvasRenderingContext2DAzure::FillRect(float x, float y, float w, float h)
     return NS_OK;
   }
 
-  bool doDrawShadow = NeedToDrawShadow();
-
   const ContextState &state = CurrentState();
 
   if (state.patternStyles[STYLE_FILL]) {
@@ -2434,8 +2454,6 @@ nsCanvasRenderingContext2DAzure::Arc(float x, float y,
 
   // Calculate the total arc we're going to sweep.
   Float arcSweepLeft = abs(endAngle - startAngle);
-  // Calculate the amount of curves needed, 1 per quarter circle.
-  Float curves = ceil(arcSweepLeft / (M_PI / 2.0f));
 
   Float sweepDirection = ccw ? -1.0f : 1.0f;
 
@@ -3017,7 +3035,7 @@ struct NS_STACK_CLASS nsCanvasBidiProcessorAzure : public nsBidiPresUtils::BidiP
     Point baselineOrigin =
       Point(point.x * devUnitsPerAppUnit, point.y * devUnitsPerAppUnit);
 
-    for (int c = 0; c < numRuns; c++) {
+    for (PRUint32 c = 0; c < numRuns; c++) {
       gfxFont *font = runs[c].mFont;
       PRUint32 endRun = 0;
       if (c + 1 < numRuns) {
@@ -3037,7 +3055,7 @@ struct NS_STACK_CLASS nsCanvasBidiProcessorAzure : public nsBidiPresUtils::BidiP
 
       float advanceSum = 0;
 
-      for (int i = runs[c].mCharacterOffset; i < endRun; i++) {
+      for (PRUint32 i = runs[c].mCharacterOffset; i < endRun; i++) {
         Glyph newGlyph;
         if (glyphs[i].IsSimpleGlyph()) {
           newGlyph.mIndex = glyphs[i].GetSimpleGlyph();
@@ -3060,7 +3078,7 @@ struct NS_STACK_CLASS nsCanvasBidiProcessorAzure : public nsBidiPresUtils::BidiP
         gfxTextRun::DetailedGlyph *detailedGlyphs =
           mTextRun->GetDetailedGlyphs(i);
 
-        for (int c = 0; c < glyphs[i].GetGlyphCount(); c++) {
+        for (PRUint32 c = 0; c < glyphs[i].GetGlyphCount(); c++) {
           newGlyph.mIndex = detailedGlyphs[c].mGlyphID;
           if (mTextRun->IsRightToLeft()) {
             newGlyph.mPosition.x = baselineOrigin.x + detailedGlyphs[c].mXOffset * devUnitsPerAppUnit -
@@ -4030,8 +4048,6 @@ nsCanvasRenderingContext2DAzure::GetImageData_explicit(PRInt32 x, PRInt32 y, PRU
     memset(aData, 0, aDataLen);
   }
 
-  bool finishedPainting = false;
-
   IntRect srcReadRect = srcRect.Intersect(destRect);
   IntRect dstWriteRect = srcReadRect;
   dstWriteRect.MoveBy(-x, -y);
@@ -4055,8 +4071,8 @@ nsCanvasRenderingContext2DAzure::GetImageData_explicit(PRInt32 x, PRInt32 y, PRU
   // from src and advancing that ptr before writing to dst.
   PRUint8 *dst = aData + dstWriteRect.y * (w * 4) + dstWriteRect.x * 4;
 
-  for (PRUint32 j = 0; j < dstWriteRect.height; j++) {
-    for (PRUint32 i = 0; i < dstWriteRect.width; i++) {
+  for (int j = 0; j < dstWriteRect.height; j++) {
+    for (int i = 0; i < dstWriteRect.width; i++) {
       // XXX Is there some useful swizzle MMX we can use here?
 #ifdef IS_LITTLE_ENDIAN
       PRUint8 b = *src++;
diff --git a/dom/interfaces/canvas/nsIDOMCanvasRenderingContext2D.idl b/dom/interfaces/canvas/nsIDOMCanvasRenderingContext2D.idl
index 2cc18ccd668..a2ad7a2cc54 100644
--- a/dom/interfaces/canvas/nsIDOMCanvasRenderingContext2D.idl
+++ b/dom/interfaces/canvas/nsIDOMCanvasRenderingContext2D.idl
@@ -79,6 +79,10 @@ interface nsIDOMCanvasRenderingContext2D : nsISupports
   void translate(in float x, in float y);
   void transform(in float m11, in float m12, in float m21, in float m22, in float dx, in float dy);
   void setTransform(in float m11, in float m12, in float m21, in float m22, in float dx, in float dy);
+  [implicit_jscontext]
+  attribute jsval mozCurrentTransform; // [ m11, m12, m21, m22, dx, dy ], i.e. row major
+  [implicit_jscontext]
+  attribute jsval mozCurrentTransformInverse;
 
   // compositing
   attribute float globalAlpha; /* default 1.0 -- opaque */