Clean up ImageBitmapRenderingContext tests 
diff --git a/imagebitmap-renderingcontext/context-creation-with-alpha.html b/imagebitmap-renderingcontext/context-creation-with-alpha.html index 88d12d1..4354b9a 100644 --- a/imagebitmap-renderingcontext/context-creation-with-alpha.html +++ b/imagebitmap-renderingcontext/context-creation-with-alpha.html 
@@ -43,7 +43,7 @@  var ctx = srcCanvas.getContext('2d');  ctx.fillStyle = 'rgba(0, 255, 0, 0.5)';  ctx.fillRect(0, 0, width, height); - createImageBitmap(srcCanvas).then(function(image) { + return createImageBitmap(srcCanvas).then(function(image) {  consumeImageBitmap(image, 'false', 0, 127, 0, 255);  });  }, "Test that an ImageBitmapRenderingContext with alpha disabled makes the canvas opaque"); @@ -55,7 +55,7 @@  var ctx = srcCanvas.getContext('2d');  ctx.fillStyle = 'rgba(0, 255, 0, 0.5)';  ctx.fillRect(0, 0, width, height); - createImageBitmap(srcCanvas).then(function(image) { + return createImageBitmap(srcCanvas).then(function(image) {  consumeImageBitmap(image, 'true', 0, 255, 0, 127);  });  }, "Test that an ImageBitmapRenderingContext with alpha enabled preserves the alpha"); @@ -67,7 +67,7 @@  var ctx = srcCanvas.getContext('2d');  ctx.fillStyle = 'rgba(0, 255, 0, 0.5)';  ctx.fillRect(0, 0, width, height); - createImageBitmap(srcCanvas).then(function(image) { + return createImageBitmap(srcCanvas).then(function(image) {  consumeImageBitmap(image, '', 0, 255, 0, 127);  });  }, "Test that the 'alpha' context creation attribute is true by default");