Implement handlified String::Equals and Name::Equals.

Implement handlified String::Equals and Name::Equals.

R=ulan@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=20669

[Yang, 2014-04-08 14:24:41]

Also removes the last use of non-handlified String::TryFlatten

[ulan, 2014-04-10 13:59:26]

lgtm

https://codereview.chromium.org/225823003/diff/1/src/api.cc
File src/api.cc (right):

https://codereview.chromium.org/225823003/diff/1/src/api.cc#newcode2998
src/api.cc:2998: i::String::Equals(i::Handle<i::String>::cast(obj),
Since you have the isolate, you could as well pass to the handle constructor.

[Yang, 2014-04-11 07:27:48]

Committed patchset #2 manually as r20669 (presubmit successful).