We now represent the SameValue operation explicitly in TurboFan and the
operation can thus participate in all kinds of optimizations. Especially
we get rid of the JSCall node in the general case, which blocks several
optimizations across the call. The general, baseline performance is now
always on par with StrictEqual.

Once the StrictEqual operator is also a simplified operator, we should
start unifying the type based optimizations in SimplifiedLowering.

In the micro-benchmark we go from

  testStrictEqual: 1422 ms.
  testObjectIs: 1520 ms.
  testManualSameValue: 1759 ms.

to

  testStrictEqual: 1426 ms.
  testObjectIs: 1357 ms.
  testManualSameValue: 1766 ms.

which gives the expected result.

Bug: v8:7007
Change-Id: I0de3ff6ff6209ab4c3edb69de6a16e387295a9c8
Reviewed-on: https://chromium-review.googlesource.com/741228Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48994}