Improves code coverage of bytecode array builder and constant
array builder.

Fixes initial index for constant pool slice for kQuad operands.

BUG=v8:4280,chromium:599000
LOG=N
TBR=rmcilroy@chromium.org

Review URL: https://codereview.chromium.org/1845313002

Cr-Commit-Position: refs/heads/master@{#35201}