Fix injecting script into all frames within <webview>.
This broke after we added the check to match frame's src against
<webview>'s src.
We shouldn't be doing this for non top level frames.
This CL also makes skipping multiple loadstop-s from utils.js configurable, the option can be truned on by setting
config.SKIP_MULTIPLE_LOADSTOP = true;
BUG=433948
Test=<webview>.executeScript with allFrames: true should inject script into all frames
Review URL: https://codereview.chromium.org/
792603002
Cr-Commit-Position: refs/heads/master@{#307651}