Move relevent JS tests to mojo_js_unittests

BUG=none
TEST=none
R=viettrungluu@chromium.org, vtl@chromium.org

Review URL: https://codereview.chromium.org/193403003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256241 0039d316-1c4b-4281-b951-d872f2087c98
aw: Always call computeScrollOffset for fling state

Apparently computeScrollAndAbsorbGlow can be skipped in certain
situation and we would be stuck in fling state forever.

BUG=
NOTRY=true

Review URL: https://codereview.chromium.org/193243002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256242 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256241
SVN changes up to revision 256242