Fix Mac build

Update `flutter start` to `flutter run`

These commands are the same, but `run` is the new hotness.

Teach SkyShell about .packages files

Don't crash on Dart compile errors

Update base to pull in fixes for toolchain: clang_i386

Instead, just unwind as usual.

Fixes #2890

SkyShell now supports --packages instead of --package-root.

Support the JNI bridge in secondary isolates

This requires detaching from the JVM at thread shutdown using a callback
that was recently added to the Dart VM.

Add a --use-glfw flag to //sky/tools/gn

This flag makes it easier to enable the glfw configuration.

Also, fix an unrelated build error in loader.cc.

Teach sky_snapshot about .packages

The sky_snapshot tool now understands the --packages command-line flag.

Progress on https://github.com/flutter/flutter/issues/1351

Remove one type-related lint

We currently whitelist some types that don't need parameters. Turning on
this lint causes too many lint errors in Atom.

Sync lint rules with `flutter analyze`

This patch updates _embedder.yaml to enforce the same set of lints as
`flutter analyze`. We're still not enabling strong mode via this
mechanism, but we might consider that in a later patch.

Related to https://github.com/flutter/flutter/issues/2687

Directly load the bundle at a known path instead of doing a search by identifier.

Also fixes an issue where a error would get logged even though loading from the precompiled application bundle was successful.

Update to GLFW 3.2

The Material Gallery is now fully interactive.

Explicitly load and unload the precompiled code bundle.

If called via `bundleWithIdentifier:` the bundle may not have been loaded. This makes it explicit.

This patch teaches //sky/shell how to integrate with the GLFW runloop. After
this patch, we can correctly resize the GLFW window.

Add GLFW platform to //sky/shell

Add GLFW support to //ui/gl

This patch is the first step towards getting the GLFW configuration up and
running.

Be explicit about the sysroot in the toolchain definition instead of inferring the same from active arguments.

Be explicit about the sysroot in the toolchain definition instead of inferring the same from active arguments.

Remove unused toolchain definitions.

Add a ios_clang_x64 toolchain definition for iOS simulator builds

Earlier, the default arm toolchain was modified depending on whether the use_ios_simulator flag was set. This was causing issues with mutliarch GN builds.