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 2e2744859061dcae407659a1983cb912ca5ec2e4..b621d2b05d96e97023e60d57c4cbab32a21df641 100644
--- a/LayoutTests/fast/canvas/canvas-createImageBitmap-drawImage.html
+++ b/LayoutTests/fast/canvas/canvas-createImageBitmap-drawImage.html
@@ -141,7 +141,7 @@ function loaded() {
         elements = [image, aCanvas, d, aCtx, testBitmap];
 
         // with all of these checks
-        checks = [checkNoCrop, checkCrop, checkCropRight, checkOverCrop, checkOverCropRight, checkNegativeCrop, checkEmpty, checkEmpty2, checkImmutable];
+        checks = [checkNoCrop, checkCrop, checkCropRight, checkOverCrop, checkOverCropRight, checkNegativeCrop, checkEmpty, checkEmpty2];
 
         // wait for callback to finish before each check to ensure synchronous behavior
         nextCheck();
@@ -425,34 +425,6 @@ function callbackEmpty(imageBitmap) {
     commonCallback(imageBitmap);
 }
 
-function callbackImmutable(imageBitmap) {
-    // change the underlying element to ensure that it does not change the imageBitmap
-    switch(i) {
-    case 0: // image
-        image = new Image();
-        break;
-    case 1: // canvas
-        clearContext(aCtx);
-        break;
-    case 2: // data
-        d = 0;
-        break;
-    case 3: // context
-        clearContext(aCtx);
-        break;
-    case 4: // bitmap
-        testBitmap = 0;
-        break;
-    default:
-        testFailed("Default should not be called.");
-    }
-    // should be drawn to (0, 0), (20, 20)
-    callbackNoCrop(imageBitmap);
-
-    // we potentially cleared our auxillary context, so redraw the image
-    drawPattern(aCtx);
-}
-
 function commonCallback(imageBitmap) {
     bitmap = imageBitmap;
     shouldBeType("bitmap", "ImageBitmap");