Avoid verifying heap while sweeper is running.

Verifier cannot handle a combination of dead+unswept objects and dead+swept objects.
* Verify before marking, before sweeping, and after a non-concurrent sweep.
* Disable pre/post-scavenge verification when concurrently sweeping.
* On shutdown, wait until concurrent GC tasks finish before verifying.

R=iposva@google.com
TBR=iposva@google.com

Review URL: https://codereview.chromium.org//631013002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@40946 260f80e4-7a28-3924-810f-c04153c831b5
Enable concurrent sweep for ia32.

R=iposva@google.com

Review URL: https://codereview.chromium.org//631023002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@40947 260f80e4-7a28-3924-810f-c04153c831b5
Remove references to Engine classes from protocol.dart

R=brianwilkerson@google.com, paulberry@google.com, danrubel@google.com
BUG=

Review URL: https://codereview.chromium.org//628293004

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@40948 260f80e4-7a28-3924-810f-c04153c831b5
Add SingleStringLiteral with accessors.

R=brianwilkerson@google.com
BUG=

Review URL: https://codereview.chromium.org//630163004

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@40949 260f80e4-7a28-3924-810f-c04153c831b5
Isolate documentation.

The Isolate class had no documentation.

BUG= http://dartbug.com/15589
R=sgjesse@google.com

Review URL: https://codereview.chromium.org//636523002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@40950 260f80e4-7a28-3924-810f-c04153c831b5
Change IsolateSpawnException to not wrap message in single quotes.

Now just add the message verbatim after "IsolateSpawnException: ".

Also make constructor non-const (error types should never be const)
and make message public.

BUG= http://dartbug.com/12689
R=sgjesse@google.com

Review URL: https://codereview.chromium.org//632233002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@40951 260f80e4-7a28-3924-810f-c04153c831b5
Don't expect single quote around IsolateSpawnException message in tests.

The single quote was removed in a previous CL.

R=sgjesse@google.com

Review URL: https://codereview.chromium.org//638513002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@40952 260f80e4-7a28-3924-810f-c04153c831b5