Don't treat Persistent as Handle in StringCache.

Get rid of hacks by pushing ReturnValue down in the call chain to where the
handles are, so that we can set it directly without copying.

We still need functions like v8String, because sometimes we need to construct an
array of handles instead of setting a return value from one handle.

BUG=236290

Review URL: https://chromiumcodereview.appspot.com/18336004

git-svn-id: svn://svn.chromium.org/blink/trunk@153510 bbb929c8-8fbe-4397-9dbb-9b2b20218538
[DevTools] Added button to console to reset console filters.

BUG=255455

Review URL: https://chromiumcodereview.appspot.com/18566002

git-svn-id: svn://svn.chromium.org/blink/trunk@153511 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Really remove ACCELERATED_OVERFLOW_SCROLLING

https://chromiumcodereview.appspot.com/14773036 removed most of the
code but left over the property / value declaration as well as a
now-dead UseCounter.

Review URL: https://chromiumcodereview.appspot.com/18581006

git-svn-id: svn://svn.chromium.org/blink/trunk@153512 bbb929c8-8fbe-4397-9dbb-9b2b20218538