Avoid useless call to v8::Isolate::GetCurrent() in ScriptPromiseResolver

Avoid useless call to v8::Isolate::GetCurrent() in ScriptPromiseResolver by
retrieving the isolate from the ScriptExecutionContext.

R=haraken
BUG=263412

Review URL: https://chromiumcodereview.appspot.com/24212004

git-svn-id: svn://svn.chromium.org/blink/trunk@158118 bbb929c8-8fbe-4397-9dbb-9b2b20218538
tables/mozilla/other/slashlogo.html is slow on WinXP

Return slow expectation that was removed at r158050.

BUG=295711
TBR= dpranke@chromium.org

Review URL: https://codereview.chromium.org/24323002

git-svn-id: svn://svn.chromium.org/blink/trunk@158119 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Use the platform=linux code path for other Unix-like platforms (FreeBSD and OpenBSD) as well, not just OS(LINUX) - with the exception of MacOS.

As a side benefit this change removes code that was not tested by any of the existing bots.

Review URL: https://chromiumcodereview.appspot.com/23537045

git-svn-id: svn://svn.chromium.org/blink/trunk@158120 bbb929c8-8fbe-4397-9dbb-9b2b20218538