Speed up JS comparison operations

Remove the not used context parameter where possible, and
simplify the NaN != NaN case.

Change-Id: I05e9639f7bac4bb1db2f33d70f063c71561ffd34
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>
Remove context argument from most binops

Change-Id: I4fa2636f1b2c8e8426b64d6e16bc7c223e6f327a
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>
Optimize the JS == operator

Implement the isEqualTo vtable method for
String, and use that to compare strings and
objects in the == implementation in one go.

Change-Id: I823ae5c4ed0683105e7a6fc5b414db92d1766fc4
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>