DevTools: teach network UISourceCodes to return metadata
The patch teaches network-based UISourceCodes to return non-null
metadata.
For the resource-based UISourceCodes, the metadata simply comes
from the underlying resource.
For the sourcemap-originating UISourceCodes which content was
embedded in the sourcemap, the contentSize metadata is available.
Drive-By: improve complexity of WI.ResourceTreeModel.resourceForURL
from O(|resources|) to O(|frames|).
BUG=none
Committed:
https://crrev.com/a22a11e3879975ab54daa514193934e4b32a966e
Cr-Commit-Position: refs/heads/master@{#425540}