DevTools: [SSP] implement "add rule to end" of arbitrary style sheet.

The patch adds long click behavior to the "add new rule" button, which
opens a list of user stylesheets where you can add a new rule.

BUG=402461

Review URL: https://codereview.chromium.org/529553002

git-svn-id: svn://svn.chromium.org/blink/trunk@181552 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Revert of [oilpan]: optimize the way we allocate persistent handles in wrappers. (patchset #6 id:100001 of https://codereview.chromium.org/525353002/)

Reason for revert:
Reverting due to browser test failures.

Original issue's description:
> [oilpan]: optimize the way we allocate persistent handles in wrappers.
> 
> The oilpan JS wrappers all have a persistent which is used to keep the wrapped object around while there is a javascript reference to it. Allocation of these wrapper persistents showed up in some of benchmarks. This change creates a new optimized WrapperPersistent which is allocated in blocks. This gives a speedup ranging between a few percent to 20% in some of the more wrapper intensive tests.
> 
> R=ager@chromium.org, haraken@chromium.org, oilpan-reviews@chromium.org, zerny@chromium.org
> BUG=
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=181298

TBR=ager@chromium.org,haraken@chromium.org,oilpan-reviews@chromium.org,zerny@chromium.org,erik.corry@gmail.com,fdegans@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=411240

Review URL: https://codereview.chromium.org/553483004

git-svn-id: svn://svn.chromium.org/blink/trunk@181553 bbb929c8-8fbe-4397-9dbb-9b2b20218538