Inlines some functions to improve reduce the stack requirements for
chains of binary operations in the bytecode generator, thereby
enabling support of deeper expression stacks.

BUG=chromium:731861

Change-Id: I5ca437d507e9b2a7eb74f33deaa708ecd646077b
Reviewed-on: https://chromium-review.googlesource.com/541356
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46080}