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* @suppress reportUnknownTypes for code using |arguments|, which is not well-handled by the JSCompiler type system.
* Fix up ad hoc documentation into proper JSDoc annotation so the type system doesn't get hung up.

R=garykac@chromium.org
BUG=none

Review URL: https://codereview.chromium.org/1204023003

Cr-Commit-Position: refs/heads/master@{#336044}