Avoid the useless strict equality comparisons with true/false being
generated for the JumpIfTrue, JumpIfFalse, JumpIfToBooleanTrue and
JumpIfToBooleanFalse bytecodes. Instead feed the accumulator (or the
outcome of ToBoolean) directly to the Branch node and do the negation
as part of the control flow.

The previous subraphs would render the loop variable analysis useless,
and would cause a lot of unnecessary bit materialization, because many
of our optimizations don't kick in.

Note: This is only part of the problem, there are more subtle differences
in the bytecode pipeline that prevent several important optimizations to
kick in.

R=mstarzinger@chromium.org
BUG=v8:5267,v8:5348

Review-Url: https://codereview.chromium.org/2309733002
Cr-Commit-Position: refs/heads/master@{#39151}