Shuffle method declarationss in Frame/LocalFrame to group virtuals.

virtual methods are currently just randomly scattered, which makes code
comprehension more difficult than it has to be. The order of definitions
has also been changed to match the order of declarations.

BUG=none

Review URL: https://codereview.chromium.org/652743011

git-svn-id: svn://svn.chromium.org/blink/trunk@184029 bbb929c8-8fbe-4397-9dbb-9b2b20218538