Allow eviction of ImageBitmaps that are created from ImageElements.

LayoutTests/fast/canvas/canvas-createImageBitmap-drawImage.html

Index: LayoutTests/fast/canvas/canvas-createImageBitmap-drawImage.html
diff --git a/LayoutTests/fast/canvas/canvas-createImageBitmap-drawImage.html b/LayoutTests/fast/canvas/canvas-createImageBitmap-drawImage.html
index 08ecd2caaa49ede0ed62550148aad23c2a2f4b3f..2e383e1870995f7ebf23cdc3585a21881667acfa 100644
--- a/LayoutTests/fast/canvas/canvas-createImageBitmap-drawImage.html
+++ b/LayoutTests/fast/canvas/canvas-createImageBitmap-drawImage.html
@@ -97,6 +97,13 @@ aCanvas.setAttribute("height", "200");
 var aCtx = aCanvas.getContext("2d");
 drawPattern(aCtx);
 
+var bCanvas = document.createElement("canvas");
+bCanvas.setAttribute("width", "200");
+bCanvas.setAttribute("height", "200");
+var bCtx = bCanvas.getContext("2d");
+bCtx.fillStyle = 'red';
+bCtx.fillRect(0, 0, 200, 200);
+
 var canvas = document.createElement("canvas");
 canvas.setAttribute("width", "500");
 canvas.setAttribute("height", "500");
@@ -388,25 +395,28 @@ function callbackImmutable(imageBitmap) {
     // change the underlying element to ensure that it does not change the imageBitmap
     switch(i) {
     case 0: // image
-        image = new Image();
+        image.onload = function() { callbackNoCrop(imageBitmap); }
+        image.src = bCanvas.toDataURL();
         break;
     case 1: // canvas
         clearContext(aCtx);
+        callbackNoCrop(imageBitmap);
         break;
     case 2: // data
         d = 0;
+        callbackNoCrop(imageBitmap);
         break;
     case 3: // context
         clearContext(aCtx);
+        callbackNoCrop(imageBitmap);
         break;
     case 4: // bitmap
         testBitmap = 0;
+        callbackNoCrop(imageBitmap);
         break;
     default:
         testFailed("Default should not be called.");
     }
-    // should be drawn to (0, 0), (200, 200)
-    callbackNoCrop(imageBitmap);
 
     // we potentially cleared our auxillary context, so redraw the image
     drawPattern(aCtx);