[runtime] Replace the EQUALS builtin with proper Object::Equals.

[runtime] Replace the EQUALS builtin with proper Object::Equals.

Move the implementation of the Abstract Equality Comparison to the
runtime and thereby remove the EQUALS dispatcher builtin. Also remove
the various runtime entry points that were only used to support the
EQUALS builtin.

Now the Abstract Equality Comparison is also using the correct
ToPrimitive implementation, which properly supports @@toPrimitive.

CQ_INCLUDE_TRYBOTS=tryserver.v8:v8_linux_layout_dbg,v8_linux_nosnap_dbg
R=mstarzinger@chromium.org
BUG=v8:4307
LOG=n

Review URL: https://codereview.chromium.org/1337993005

Cr-Commit-Position: refs/heads/master@{#30747}