Moved imagebitmap from module to core.

Since window in core depends on imagebitmap in module, we need to move imagebitmap from module to core.

i.e. Window implements ImageBitmapFactories;

BUG=358074

Review URL: https://codereview.chromium.org/428853002

git-svn-id: svn://svn.chromium.org/blink/trunk@179561 bbb929c8-8fbe-4397-9dbb-9b2b20218538