33374 Devfs cleanup and testing (cla: yes, tool)

33377 Compatibility pass on flutter/widgets tests for JavaScript compilation. (8) (a: tests, cla: yes, ☸ platform-web)

33378 Compatibility pass on flutter/material tests for JavaScript compilation. (9) (a: tests, cla: yes, ☸ platform-web)

33403 Add blank newline after Dartdoc bulleted list. (cla: yes)

33406 Add web safe indirection to Platform.isPlatform getters (a: tests, cla: yes, framework)

33431 Expose service client and app isolate in driver (cla: yes, framework, t: flutter driver)

33442 fix GridView documentation (cla: yes, d: api docs, framework, waiting for tree to go green)