[runtime] Replace COMPARE/COMPARE_STRONG with proper Object::Compare.

[runtime] Replace COMPARE/COMPARE_STRONG with proper Object::Compare.

This removes the weird COMPARE and COMPARE_STRONG JavaScript builtins
and replaces them with a proper C++ implementation in Object::Compare
and appropriate wrappers Object::LessThan, Object::GreaterThan, and
friends that are intended to be used by a true/false returning CompareIC
in the future, as well as the interpreter.  As a short-term solution we
provide %Compare and %Compare_Strong entry points for the current
CompareIC that return the appropriate integer values expected by
fullcodegen currently.

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

BUG=v8:4307
LOG=n

Review URL: https://codereview.chromium.org/1350113002

Cr-Commit-Position: refs/heads/master@{#30816}