Document additional Closure Compiler tags

[hegemonic]

We're adding support for a bunch of Closure Compiler tags in JSDoc 3.6.0. This issue lists the tags that need to be documented. All of these are Closure Compiler-only unless otherwise noted.

• @define
• @dict (no-op)
• @export (no-op)
• @externs (no-op)
• @fileoverview (already documented as a synonym for @file)
• @final (supported since 3.3.0 as a Closure Compiler-only synonym for @readonly)
• @implicitCast (no-op)
• @modifies (JSDoc and Closure Compiler)
• @noalias (no-op)
• @nocollapse (no-op)
• @nocompile (no-op)
• @nosideeffects
• @polymer (no-op)
• @polymerBehavior (no-op)
• @preserve (synonym for @license)
• @public (document that it allows a type for Closure Compiler)
• @record (treated as a synonym for @interface)
• @struct (no-op)
• @suppress (no-op)
• @template (no-op)
• @this (different semantics than JSDoc)
• @typedef (different semantics than JSDoc)
• @unrestricted (no-op)

[hegemonic]

On second thought, I don't really want to add new pages for all of these tags, given that:

• JSDoc just ignores most of them
• Most JSDoc users won't care about these tags

Maybe we should just do this:

• Add a new page about JSDoc's support for Closure Compiler annotations
• Add or update the tag pages for tags that actually do something