Port 411c5b7f

Original commit message:
    Also remove the ResultMode from ToBooleanStub and always return true or
    false and use the same mechanism in fullcodegen.  This is in preparation
    for adding ToBoolean hints to TurboFan.

    Drive-by-fix: We can use the power of the ToBooleanIC in TurboFan now
    that the ResultMode is gone (and the runtime always returns true or
    false from the miss handler).

R=bmeurer@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=v8:4583
LOG=n

Review URL: https://codereview.chromium.org/1490363003

Cr-Commit-Position: refs/heads/master@{#32531}