Mixed Content: Add a static check for WebSockets.
This patch migrates the WebSocket check to a static method, which enables
us to get rid of `canRunInsecureContent`. There should be no behavioral
change for insecure WebSockets, other than a change to the console message
which aligns it with the message for other resource types.
As a side-effect of reorganizing the frame checks, we also fixed a small
bug that output console messages for both the top frame _and_ the child
frame when mixed content was detected. Now we output a message for the
document in which the content is loaded, even if the top-level document
caused the secure context.
BUG=
411184
Committed:
https://src.chromium.org/viewvc/blink?view=rev&revision=188054