51307 [flutter_tools] add more search paths for source maps (cla: yes, tool)

51314 Update flexible_space_bar.dart (cla: yes, d: api docs, documentation, f: material design, framework, waiting for tree to go green)

51330 Update covariant_templates_test after changes to TypeError. (cla: yes, framework)

51335 Add width constraints for FlexibleSpaceBar.title in its expanded state, so that overflow of long titles can be handled (cla: yes, f: material design, framework, waiting for tree to go green)

51346 [flutter_tools] don’t fix chrome window size, add more logs (cla: yes, tool)

51375 Extend the gen_l10n integration test (a: internationalization, cla: yes, tool, waiting for tree to go green)