CL:6574464 changed BridgedContentView::hitTest: to use GetHitTestResult(), which
returns kRootView for any non-null, non-NativeViewHost view — causing
BridgedContentView to absorb all web content mouse events. In BrowserWindow,
content_view_ sits in front of the sibling WebContentsView and covers the full
client area, so it was always found first, breaking all loadURL page interaction.

Fix this by installing a ContentViewTargeterDelegate on content_view_ in
NativeWindowMac::SetContentView that returns nullptr (instead of the view itself)
when no children cover the target point. This makes GetHitTestResult return kOther,
allowing hitTest: to fall through to [super hitTest:] and find
RenderWidgetHostViewCocoa. This also removes the now-unnecessary chromium
partial-revert patch that worked around the same issue.

Co-authored-by: Shelley Vohr <shelley.vohr@gmail.com>