Add DartHandleCache and use it to cache strings used when converting Rect and

Add DartHandleCache and use it to cache strings used when converting Rect and
Point classes.

R=abarth@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/ff336f0c8d420dba0f78165bf77429009ec7cb3e

[Matt Perry, 2015-05-27 19:46:52]

mpcomplete@chromium.org changed reviewers:
+ abarth@chromium.org

[abarth-chromium, 2015-05-27 19:54:55]

lgtm

[Matt Perry, 2015-05-27 20:18:15]

Wait.. do we plan on only ever having one DartState/Dart isolate? I just
realized this idea won't work if we can have multiple DartStates.

[abarth-chromium, 2015-05-27 20:20:06]

On 2015/05/27 at 20:18:15, mpcomplete wrote:
> Wait.. do we plan on only ever having one DartState/Dart isolate? I just
realized this idea won't work if we can have multiple DartStates.

Oh, you're right.  We can have multiple isolates if there are multiple sky views
in a single process.

Maybe just add x() and y(), etc, accessors to DOMDartState rather than using the
fancy ID thing...

[Matt Perry, 2015-05-27 20:57:12]

Done. I had to add a callback for when the isolate is created, so we know when
its safe to alloc the dart strings.

[abarth-chromium, 2015-05-27 23:33:50]

lgtm

[Matt Perry, 2015-05-28 17:39:37]

Committed patchset #3 (id:40001) manually as
ff336f0c8d420dba0f78165bf77429009ec7cb3e (presubmit successful).