[Interpreter] Fixes PreviousBytecodeHelper to check if previous bytecode is in the same basic block.

PreviousBytecodeHelper used to return Bytecode::kLast if the previous bytecode was not
in the same basicblock. Changed it to be instantiated only when the previous bytecode
is in the same basic block.

BUG=v8:4280
LOG=N

Review URL: https://codereview.chromium.org/1510553002

Cr-Commit-Position: refs/heads/master@{#32702}