Remove dependency on Chrome ScriptID

As of https://github.com/dart-lang/webdev/pull/1078 we no longer require the scriptID to set breakpoints. However, we still depend on the scriptID provided in the JS frames to translate them to Dart frames. However, the script URL is also provided in the JS frames which should provide enough information to do the translation. Removing our dependency on the script ID will greatly improve the IPL of Dart DevTools as we will no longer saturate the Debug Extension connection with these `ScriptParsed` events.

Start by tracing how JavaScript frames are translated to Dart frames and where the frame script URL and ScriptID are consumed. Confirm the translation can use the script URL alone, and verify that the workflow no longer depends on ScriptParsed events or saturates the Debug Extension connection.

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