This actually fixes 3 different issues when accessing Operand1:

   * Object vs. HeapObject

   * Wrong defaults for equals/hash

   * silently dropping const

TEST=test/mjsunit/regress/regress-441099.js
BUG=chromium:441099
LOG=y

Review URL: https://codereview.chromium.org/812563002

Cr-Commit-Position: refs/heads/master@{#25843}