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

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

Port 54bab695f5de5bf5948c5b50b217628a00d60f91

Original commit message:
    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.

R=bmeurer@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, dstence@us.ibm.com
BUG=v8:4307
LOG=n

Review URL: https://codereview.chromium.org/1357493002

Cr-Commit-Position: refs/heads/master@{#30810}