Reland "Track field types.".

Reland "Track field types.".

This is an initial step towards tracking the exact types instead of just
the representations of fields. It adds support to track up to one map of
heap object field values, eliminating various map checks on values
loaded from such fields, at the cost of making stores to such fields
slightly more expensive.

Issues with transitioning stores and fast object literals in Crankshaft
fixed.

TEST=mjsunit/field-type-tracking
R=svenpanne@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=20746

[Benedikt Meurer, 2014-04-15 07:10:34]

PTAL

[Sven Panne, 2014-04-15 07:36:19]

LGTM (mostly rubber-stamped)

[Benedikt Meurer, 2014-04-15 07:37:05]

Committed patchset #3 manually as r20746 (presubmit successful).