destroy “remote” webcontents on GC

auditors @bbondy

Bump v4.5.20+63.0.3239.59

Bump v4.5.19+63.0.3239.59

Bump v4.5.18+63.0.3239.40

Bump v4.5.17+62.0.3202.94

Bump v4.5.16+62.0.3202.94

Merge pull request brave#381 from brave/browser-laptop-issue-11331

Send key event to menu when webview focused

Bump v4.5.14+62.0.3202.75

Bump v4.5.13+62.0.3202.75

Bump v4.5.12+62.0.3202.75