actually pause webkit thread, remove costly invalidate

pass isScrolling info to glwebviewstate
pause webkit in a way that doesn't require full inval on resume

depends on change https://android-git.corp.google.com/g/#/c/130210/

bug:5106313
Change-Id: Icbe57e3a163c17c99bd1ea49ab42e40f9d41cc6d
2 files changed