Bug 1266808 - throw exception when canvas.drawImage passed closed ImageBitmap r=baku

Fixed breakages with clipped areas disjoint to image
Fixed text case that didn't expect exception
Fixed coding style

Differential Revision: https://phabricator.services.mozilla.com/D31048

dom/canvas/CanvasRenderingContext2D.cpp

@@ -4422,6 +4422,9 @@ void CanvasRenderingContext2D::DrawImage(const CanvasImageSource& aImage,
     srcSurf = imageBitmap.PrepareForDrawTarget(mTarget);
 
     if (!srcSurf) {
+      if (imageBitmap.IsClosed()) {
+        aError.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+      }
       return;
     }
 

dom/canvas/ImageBitmap.h

@@ -141,6 +141,7 @@ class ImageBitmap final : public nsISupports, public nsWrapperCache {
   void OnShutdown();
 
   bool IsWriteOnly() const { return mWriteOnly; }
+  bool IsClosed() const { return !mData; };
 
  protected:
   /*

dom/canvas/test/test_imagebitmap_close.html

@@ -56,10 +56,10 @@ function runTest() {
     var canvas2 = createCanvas();
     var ctx2 = canvas2.getContext("2d");
     var beforeDrawImageDataURL = canvas2.toDataURL();
+    var _thrown = undefined; try {
       ctx2.drawImage(bmp, 0, 0);
-    var afterDrawImageDataURL = canvas2.toDataURL();
+    } catch (e) { _thrown = e };
-    ok(beforeDrawImageDataURL == afterDrawImageDataURL,
+    ok(_thrown && _thrown.name == "InvalidStateError" && _thrown.code == DOMException.INVALID_STATE_ERR, "should throw InvalidStateError");
-       "Drawing operations with a closed ImageBitmap should do nothing.");
     runTestOnWorker();
   });
 }