LOG=N
BUG=

Review-Url: https://codereview.chromium.org/2135573002
Cr-Commit-Position: refs/heads/master@{#37676}

Adds back simple dead code elimination to the bytecode pipeline.

BUG=v8:4280,chromium:616064

Review-Url: https://codereview.chromium.org/2038083002
Cr-Commit-Position: refs/heads/master@{#37147}

With this change the bytecode array builder only emits expression
positions for bytecodes that can throw. This allows more peephole
optimization opportunities and results in smaller code.

BUG=v8:4280,chromium:615979
LOG=N

Review-Url: https://codereview.chromium.org/2038323002
Cr-Commit-Position: refs/heads/master@{#36863}

The optimization stages in the bytecode generation pipeline must
preserve source position information. Failure to preserve
source position information could result in single stepping
in the debugger misbehaving or mis-reporting in exception stack traces.

This change adds tests intended to check optimizations do not damage
source position info.

BUG=v8:4280
LOG=N

Review-Url: https://codereview.chromium.org/2042633002
Cr-Commit-Position: refs/heads/master@{#36855}