Bug 1239799 part 2: Add support for @media(-webkit-transform-3d) media query, for web compatibility. r=heycam

dom/base/nsGkAtomList.h

@@ -1222,6 +1222,7 @@ GK_ATOM(tr, "tr")
 GK_ATOM(track, "track")
 GK_ATOM(trailing, "trailing")
 GK_ATOM(transform, "transform")
+GK_ATOM(transform_3d, "transform-3d")
 GK_ATOM(transformiix, "transformiix")
 GK_ATOM(translate, "translate")
 GK_ATOM(transparent, "transparent")

layout/style/nsMediaFeatures.cpp

@@ -324,6 +324,15 @@ GetDevicePixelRatio(nsPresContext* aPresContext, const nsMediaFeature*,
   return NS_OK;
 }
 
+static nsresult
+GetTransform3d(nsPresContext* aPresContext, const nsMediaFeature*,
+               nsCSSValue& aResult)
+{
+  // Gecko supports 3d transforms, so this feature is always 1.
+  aResult.SetIntValue(1, eCSSUnit_Integer);
+  return NS_OK;
+}
+
 static nsresult
 GetSystemMetric(nsPresContext* aPresContext, const nsMediaFeature* aFeature,
                 nsCSSValue& aResult)
@@ -533,6 +542,15 @@ nsMediaFeatures::features[] = {
     { nullptr },
     GetDevicePixelRatio
   },
+  // -webkit-transform-3d:
+  {
+    &nsGkAtoms::transform_3d,
+    nsMediaFeature::eMinMaxNotAllowed,
+    nsMediaFeature::eBoolInteger,
+    nsMediaFeature::eHasWebkitPrefix,
+    { nullptr },
+    GetTransform3d
+  },
 
   // Mozilla extensions
   {

layout/style/test/test_media_queries.html

@@ -440,6 +440,8 @@ function run() {
   expression_should_be_parseable("-webkit-max-device-pixel-ratio: 1.0");
   expression_should_not_be_parseable("max-device-pixel-ratio: 1.0");
 
+  should_apply("(-webkit-transform-3d)");
+
   features = [ "max-aspect-ratio", "device-aspect-ratio" ];
   for (i in features) {
     feature = features[i];