[android] Fix broken `--android-skip-build-dependency-validation` flag (#172581)

The way I was parsing the boolean previously was just not working. This
works.

Also restores a set of tests that was deleted in
https://github.com/flutter/flutter/pull/171776 that I don't think should
have been (missed this in review), and adds a test case for the fix.

Added as bringup because the name is changed, but I ran the tests
locally and they pass.

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

---------

Co-authored-by: Gray Mackall <mackall@google.com>
https://dart.googlesource.com/external/github.com/flutter/flutter/+/df99f53bc051b18eef0e892e83adce53cc90ccc9
diff --git a/DEPS b/DEPS
index fd22090..e7ad02d 100644
--- a/DEPS
+++ b/DEPS
@@ -231,7 +231,7 @@
 deps = {
   'flutter/engine/src/flutter/third_party/dart': Var('dart_git') + '/sdk' + '@' + 'e4e36a396b7302d92530bf8dee4dea9dcc9771c9',
 
-  'flutter': Var('flutter_git') + '/mirrors/flutter' + '@' + '5d00045ad2656e1164fc60d006a084ba42353362',
+  'flutter': Var('flutter_git') + '/mirrors/flutter' + '@' + 'df99f53bc051b18eef0e892e83adce53cc90ccc9',
 
   'flutter/engine/src/flutter/third_party/depot_tools':
   Var('chromium_git') + '/chromium/tools/depot_tools.git' + '@' + '580b4ff3f5cd0dcaa2eacda28cefe0f45320e8f7',
diff --git a/commits.json b/commits.json
index 39d22ea..1e76376 100644
--- a/commits.json
+++ b/commits.json
@@ -1,4 +1,4 @@
 {
-  "flutter":"5d00045ad2656e1164fc60d006a084ba42353362",
+  "flutter":"df99f53bc051b18eef0e892e83adce53cc90ccc9",
   "flutter/engine/src/flutter/third_party/dart":"e4e36a396b7302d92530bf8dee4dea9dcc9771c9"
 }
\ No newline at end of file