Verify that JavaScript sourcemap enabling and disabling adds/removes sourcemap sources.


Running: dumpInitialNavigator
top
  127.0.0.1:8000
    devtools
      resources
        inspected-page.html
      sources/resources
        sourcemap-script.js
        sourcemap-typescript.ts

Running: disableJSSourceMaps
top
  127.0.0.1:8000
    devtools
      resources
        inspected-page.html
      sources/resources
        sourcemap-script.js

Running: enableJSSourceMaps
top
  127.0.0.1:8000
    devtools
      resources
        inspected-page.html
      sources/resources
        sourcemap-script.js
        sourcemap-typescript.ts