Cache ElementLocation instance and index key/location ids.

This saves us about 9% of time, as the previous CL.
From 22294 ms to 20040 ms.

R=brianwilkerson@google.com
BUG=

Review URL: https://codereview.chromium.org//739643003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41814 260f80e4-7a28-3924-810f-c04153c831b5
Implement enum types in VM

Fully support enum types as per language spec version 1.6.

R=srdjan@google.com

Review URL: https://codereview.chromium.org//735723003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41815 260f80e4-7a28-3924-810f-c04153c831b5
Placate linux C++ compiler

Fixes build error on Linux.

TBR

Review URL: https://codereview.chromium.org//732423005

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41816 260f80e4-7a28-3924-810f-c04153c831b5
Process two 32-bit digits as one 64-bit digit in bigint absAdd and absSub
intrinsic on x64. More to follow.
Added assembler instructions and tests.

R=zra@google.com

Review URL: https://codereview.chromium.org//732663003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41817 260f80e4-7a28-3924-810f-c04153c831b5