WebView: misc docs changes in WebViewClient

No change to logic.

This CL has miscellaneous docs changes for WebViewClient.java:

 * Spelling
 * Codify some terms ({@code } annotations)
 * Linkify references to other methods

Test: make docs (all links work, things look better)
Change-Id: Ia748a258a29b467b9655c018b5783b5b22fad0eb