We seem to get some small wins from avoiding the Ldr bytecodes, probably due
to reduced icache pressure since there are less bytecode handlers. Replace
the Ldr bytecodes with Star lookahead inlined into the Lda versions.

Also fixes IsAccumulatorLoadWithoutEffects to include LdaContextSlot and
LdaCurrentContextSlot

BUG=v8:4280

Review-Url: https://codereview.chromium.org/2489513005
Cr-Commit-Position: refs/heads/master@{#40883}