The parameter indices are shifted by 1 in BytecodeArrayBuilder
because the receiver is variable at index 0 and not -1.

Split BytecodeArrayBuilder::Parameter(index) method into
Receiver() (same as Parameter(-1)) and
Parameter(index).

This way we avoid confusing (index+1) counting in BytecodeGenerator().

BUG=

Change-Id: Id87ec7c708cecfc3108011994f3177f483772bcc
Reviewed-on: https://chromium-review.googlesource.com/461904Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Franziska Hinkelmann <franzih@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44262}