Make WebP decoding independent of stream length.

There's case, when Skia SkStream passed to WebP decoder may have
incorrect length (stream->getLength()). This is observed, if the App
decodes an image (size > 80KB) using:
'ParcelFileDescriptor --> BitmapFactory.decodeStream()'
Updated the WebP incremental decoding loop to not rely on
stream->getLength()

Change-Id: I3c7cdd1cf6483e5bb4c0211bc989e14ba8ce4457
1 file changed