Various cleanup/simplification in object-observe.js

The biggest change is the removal of the map wrapper objects:
we now operate directly on the observation weak map, since there
are already Get/GetOrCreate/Set functions for each info map.
Various other small cleanups as well, including the deletion of
unnecessary forwarding functions and making use of standard macros.

This is a reland of r24972, retaining GetObservationStateJS() to
keep snapshotting working properly.

R=rossberg@chromium.org

Review URL: https://codereview.chromium.org/663253006

Cr-Commit-Position: refs/heads/master@{#24990}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24990 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Cleanup unscheduled use count for controls of coupled nodes.

R=titzer@chromium.org, jarin@chromium.org

Review URL: https://codereview.chromium.org/687133003

Cr-Commit-Position: refs/heads/master@{#24991}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24991 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
[turbofan] Add deopt for %StringMatch

R=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/639763004

Cr-Commit-Position: refs/heads/master@{#24992}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24992 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
MIPS: EmitCreateIteratorResult loads map from function's context.

Port r24987 (cfc4713)

Original commit message:
Caching or serialization can cause full-codegen output to be shared
between contexts.  CreateIteratorResult, however, was doing the wrong
thing by creating results with the map that was current when the code
was generated.  Instead, we should chase pointers to load the right map
from the function's context.

BUG=v8:3656
LOG=N
R=paul.lind@imgtec.com

Review URL: https://codereview.chromium.org/691563002

Cr-Commit-Position: refs/heads/master@{#24993}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24993 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Add a few missing overrides found by a new clang warning.

Namely, -Winconsistent-missing-override. No behavior change.

BUG=v8:3658
LOG=N
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/688533002

Cr-Commit-Position: refs/heads/master@{#24994}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24994 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Inline trivial OperatorProperties methods.

R=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/686213002

Cr-Commit-Position: refs/heads/master@{#24995}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24995 ce2b1a6d-e550-0410-aec6-3dcde31c8c00