17080 Add support for the Metal backend on all iOS builds. (cla: yes, waiting for tree to go green)

17081 Disable Embedder11yTest::A11yTreeIsConsistent to unblock LUCI. (cla: yes)

17082 Roll src/third_party/dart ace1d9b9213a..4093d08271f6 (12 commits) (cla: yes, waiting for tree to go green)

17084 Remove the unused method on iOS surface to make the resource context current. (cla: yes, waiting for tree to go green)

17086 Roll fuchsia/sdk/core/linux-amd64 from v32mJ… to X3Xm2… (cla: yes, waiting for tree to go green)