Verify that UISourceCodes are removed as main frame gets navigated.


Running: dumpInitialWorkspace
Removed: 0 uiSourceCodes
Workspace: 2 uiSourceCodes.
    debugger:///VM[XXX]
    http://127.0.0.1:8000/devtools/resources/inspected-page.html

Running: attachFrame
Removed: 0 uiSourceCodes
Workspace: 10 uiSourceCodes.
    debugger:///VM[XXX]
[+] debugger:///VM[XXX] sourcemap-script.js
[+] debugger:///VM[XXX] _test_attachFrame.js
[+] http://127.0.0.1:8000/devtools/bindings/resources/sourcemap-frame.html
[+] http://127.0.0.1:8000/devtools/bindings/resources/sourcemap-sass.scss
[+] http://127.0.0.1:8000/devtools/bindings/resources/sourcemap-script.js
[+] http://127.0.0.1:8000/devtools/bindings/resources/sourcemap-style.css
[+] http://127.0.0.1:8000/devtools/bindings/resources/sourcemap-typescript.ts
    http://127.0.0.1:8000/devtools/resources/inspected-page.html
[+] http://127.0.0.1:8000/devtools/resources/_test_attachFrame.js

Running: navigateMainFrame
Removed: 10 uiSourceCodes
[-] debugger:///VM[XXX]
[-] debugger:///VM[XXX] sourcemap-script.js
[-] debugger:///VM[XXX] _test_attachFrame.js
[-] http://127.0.0.1:8000/devtools/bindings/resources/sourcemap-frame.html
[-] http://127.0.0.1:8000/devtools/bindings/resources/sourcemap-sass.scss
[-] http://127.0.0.1:8000/devtools/bindings/resources/sourcemap-script.js
[-] http://127.0.0.1:8000/devtools/bindings/resources/sourcemap-style.css
[-] http://127.0.0.1:8000/devtools/bindings/resources/sourcemap-typescript.ts
[-] http://127.0.0.1:8000/devtools/resources/inspected-page.html
[-] http://127.0.0.1:8000/devtools/resources/_test_attachFrame.js
Workspace: 1 uiSourceCodes.
[+] http://127.0.0.1:8000/devtools/bindings/resources/empty-page.html