Enable DOM storage for Android WebView

[rmartin16]

Changes

• To align with WebView on other platforms, enable DOM storage for Android
• I also reviewed the features detailed at https://browserleaks.com/features for all platforms; other than some WebRTC support on iOS, the WebViews are basically at parity for all platforms
• Closes Enable DOM storage in Android Webview #2767

PR Checklist:

• All new features have been tested
• All new features have been documented
• I have read the CONTRIBUTING.md file
• I will abide by the code of conduct

[rmartin16]

This test ended up being way more of a headache than I expected. Nonetheless, it seems to work now.

I tried using assert_content_change() to ensure it was safe to access local storage in javascript...but that wasn't always enough; just waiting a second has appeared reliable, though...

I was curious how this new test compares to other "long running" tests; total runtime was 190.69s.

I/python.stdout: 5.02s call     tests/widgets/test_mapview.py::test_zoom
I/python.stdout: 4.63s call     tests/widgets/test_detailedlist.py::test_refresh
I/python.stdout: 3.31s call     tests/widgets/test_mapview.py::test_location
I/python.stdout: 3.13s call     tests/test_fonts.py::test_font_options
I/python.stdout: 2.89s call     tests/widgets/test_mapview.py::test_add_pins
I/python.stdout: 2.22s call     tests/widgets/test_mapview.py::test_select_pin
I/python.stdout: 1.73s call     tests/widgets/test_table.py::test_font
I/python.stdout: 1.71s call     tests/widgets/test_table.py::test_column_changes
I/python.stdout: 1.29s call     tests/widgets/test_dateinput.py::test_change
I/python.stdout: 1.24s call     tests/widgets/test_table.py::test_headerless_column_changes
I/python.stdout: 1.22s setup    tests/widgets/test_mapview.py::test_focus_noop
I/python.stdout: 1.19s call     tests/widgets/test_scrollcontainer.py::test_manual_scroll
I/python.stdout: 1.16s setup    tests/widgets/test_mapview.py::test_zoom
I/python.stdout: 1.16s setup    tests/widgets/test_mapview.py::test_flex_widget_size
I/python.stdout: 1.14s call     tests/widgets/test_timeinput.py::test_change
I/python.stdout: 1.14s setup    tests/widgets/test_mapview.py::test_add_pins
I/python.stdout: 1.13s setup    tests/widgets/test_mapview.py::test_select_pin
I/python.stdout: 1.10s setup    tests/widgets/test_mapview.py::test_location
I/python.stdout: 1.06s call     tests/widgets/test_webview.py::test_dom_storage_enabled
I/python.stdout: 0.89s setup    tests/widgets/test_scrollcontainer.py::test_horizontal_scroll_small_content
I/python.stdout: 0.88s setup    tests/widgets/test_scrollcontainer.py::test_background_color
I/python.stdout: 0.88s setup    tests/widgets/test_scrollcontainer.py::test_scroll_both
I/python.stdout: 0.86s call     tests/widgets/test_canvas.py::test_transparency
I/python.stdout: 0.85s call     tests/widgets/test_canvas.py::test_multiline_text
I/python.stdout: 0.84s call     tests/widgets/test_table.py::test_cell_widget
I/python.stdout: 0.82s setup    tests/widgets/test_table.py::test_focus_noop

[freakboy3742]

Agreed the 1s delay isn't ideal, but it's not the worst sin in the testbed codebase by a large margin :-)

Looks good, and it's also good that we can confirm storage works on every other backend.