Bug 1224007 part 4. Fix some cases in which ErrorResult instances are destroyed without doing anything useful with exceptions on them. r=peterv

dom/base/nsGlobalWindow.cpp

@@ -6138,10 +6138,12 @@ nsGlobalWindow::FinishFullscreenChange(bool aIsFullscreen)
     mWakeLock = pmService->NewWakeLock(NS_LITERAL_STRING("DOM_Fullscreen"),
                                        this, rv);
     NS_WARN_IF_FALSE(!rv.Failed(), "Failed to lock the wakelock");
+    rv.SuppressException();
   } else if (mWakeLock && !mFullScreen) {
     ErrorResult rv;
     mWakeLock->Unlock(rv);
     mWakeLock = nullptr;
+    rv.SuppressException();
   }
 }
 
@@ -11764,6 +11766,7 @@ nsGlobalWindow::RunTimeoutHandler(nsTimeout* aTimeout,
     ErrorResult ignored;
     JS::Rooted<JS::Value> ignoredVal(CycleCollectedJSRuntime::Get()->Runtime());
     callback->Call(me, handler->GetArgs(), &ignoredVal, ignored, reason);
+    ignored.SuppressException();
   }
 
   // We ignore any failures from calling EvaluateString() on the context or

dom/base/nsGlobalWindow.h

@@ -1131,7 +1131,10 @@ public:
   {
     MOZ_ASSERT(IsOuterWindow());
     mozilla::ErrorResult ignored;
-    return GetContentInternal(ignored, /* aUnprivilegedCaller = */ false);
+    nsCOMPtr<nsIDOMWindow> win =
+      GetContentInternal(ignored, /* aUnprivilegedCaller = */ false);
+    ignored.SuppressException();
+    return win.forget();
   }
 
   void Get_content(JSContext* aCx,

dom/camera/DOMCameraControl.cpp

@@ -1276,8 +1276,6 @@ nsDOMCameraControl::OnHardwareStateChange(CameraControlListener::HardwareState a
   DOM_CAMERA_LOGT("%s:%d : this=%p\n", __func__, __LINE__, this);
   MOZ_ASSERT(NS_IsMainThread());
 
-  ErrorResult ignored;
-
   switch (aState) {
     case CameraControlListener::kHardwareOpen:
       DOM_CAMERA_LOGI("DOM OnHardwareStateChange: open\n");
@@ -1405,7 +1403,6 @@ nsDOMCameraControl::OnRecorderStateChange(CameraControlListener::RecorderState a
   DOM_CAMERA_LOGT("%s:%d : this=%p, state=%u\n", __func__, __LINE__, this, aState);
   MOZ_ASSERT(NS_IsMainThread());
 
-  ErrorResult ignored;
   nsString state;
 
   switch (aState) {

dom/canvas/CanvasRenderingContext2D.cpp

@@ -3967,6 +3967,7 @@ gfxFontGroup *CanvasRenderingContext2D::GetCurrentFontStyle()
     nsCOMPtr<nsIPresShell> presShell = GetPresShell();
     bool fontUpdated = SetFontInternal(kDefaultFontStyle, err);
     if (err.Failed() || !fontUpdated) {
+      err.SuppressException();
       gfxFontStyle style;
       style.size = kDefaultFontSize;
       gfxTextPerfMetrics* tp = nullptr;

dom/html/HTMLMediaElement.cpp

@@ -2409,6 +2409,7 @@ HTMLMediaElement::WakeLockRelease()
   if (mWakeLock) {
     ErrorResult rv;
     mWakeLock->Unlock(rv);
+    rv.SuppressException();
     mWakeLock = nullptr;
   }
 }

dom/html/HTMLVideoElement.cpp

@@ -267,6 +267,7 @@ HTMLVideoElement::UpdateScreenWakeLock()
   if (mScreenWakeLock && (mPaused || hidden || !mUseScreenWakeLock)) {
     ErrorResult rv;
     mScreenWakeLock->Unlock(rv);
+    rv.SuppressException();
     mScreenWakeLock = nullptr;
     return;
   }

dom/media/MediaRecorder.cpp

@@ -1162,6 +1162,7 @@ MediaRecorder::NotifyOwnerDocumentActivityChanged()
     // Stop the session.
     ErrorResult result;
     Stop(result);
+    result.SuppressException();
   }
 }
 

dom/workers/WorkerPrivate.cpp

@@ -496,6 +496,9 @@ private:
     ErrorResult rv;
     scriptloader::LoadMainScript(aCx, mScriptURL, WorkerScript, rv);
     if (NS_WARN_IF(rv.Failed())) {
+      // I guess suppress the exception since that's what we used to
+      // do, though this seems moderately weird.
+      rv.SuppressException();
       return false;
     }
 
@@ -532,6 +535,9 @@ private:
     JSAutoCompartment ac(aCx, global);
     scriptloader::LoadMainScript(aCx, mScriptURL, DebuggerScript, rv);
     if (NS_WARN_IF(rv.Failed())) {
+      // I guess suppress the exception since that's what we used to
+      // do, though this seems moderately weird.
+      rv.SuppressException();
       return false;
     }
 

dom/xul/templates/nsXULTemplateQueryProcessorXML.cpp

@@ -356,6 +356,7 @@ nsXULTemplateQueryProcessorXML::AddBinding(nsIDOMNode* aRuleNode,
     nsAutoPtr<XPathExpression> compiledexpr;
     compiledexpr = CreateExpression(aExpr, ruleNode, rv);
     if (rv.Failed()) {
+        rv.SuppressException();
         nsXULContentUtils::LogTemplateError(ERROR_TEMPLATE_BAD_BINDING_XPATH);
         return NS_OK;
     }

layout/base/AccessibleCaret.cpp

@@ -236,6 +236,7 @@ AccessibleCaret::RemoveCaretElement(nsIDocument* aDocument)
   ErrorResult rv;
   aDocument->RemoveAnonymousContent(*mCaretElementHolder, rv);
   // It's OK rv is failed since nsCanvasFrame might not exists now.
+  rv.SuppressException();
 }
 
 AccessibleCaret::PositionChangedResult