Make Error.prototype.toString spec compliant; and fix various side-effect-free error printing methods

R=yangguo@chromium.org
LOG=n

Committed: https://crrev.com/5dffa35350d0f57402806e6bd87a914e1d5933e4
Cr-Commit-Position: refs/heads/master@{#32695}

Review URL: https://codereview.chromium.org/1507273002

Cr-Commit-Position: refs/heads/master@{#32720}