Force reset of RenderViewImpl zoom level.
When navigation away from a page fails, the displayed error page uses
the zoom level of the current page since the underlying RenderViewImpl
is re-used without resetting its zoom level before displaying the error
page.
This CL forces the RenderViewImpl's zoom level to be reset to 0 whenever
the url being navigated to is unkown to the RenderViewImpl.
BUG=422464
Review URL: https://codereview.chromium.org/
663203002
Cr-Commit-Position: refs/heads/master@{#300352}