docs: Javadoc typo fix

Doc is staged to:

http://go/dac-stage/reference/android/webkit/WebView.html

Exempt-From-Owner-Approval: Doc-only change
Bug: 20926682
Test: make ds-docs
Change-Id: Ib966923b75c8a70da5415f38e4217caeecc44cbe
Merged-In: Ib966923b75c8a70da5415f38e4217caeecc44cbe