Test to catch Canvas 2D API changes. If this test should ever fail, we should re-examine the Canvas 2D state saving/restoring logic in the InjectedScriptModule to include any latest changes to the API.
New properties and functions that should be manually examined (should be empty to pass the test):
+addHitRegion
+clearHitRegions
currentTransform
drawFocusIfNeeded
ellipse
isContextLost
+removeHitRegion
resetTransform
scrollPathIntoView
webkitImageSmoothingEnabled