Support for setting Content-Type of POST requests

KeyboardServiceState#setSelection shouldn't crash

Now we sanity check our inputs instead of crashing.

Fixes #1033

Dart/JNI: improve Java method lookup

Add third_party/firebase to gitignore

RawKeyboardService leaks

The removeListener function didn't actually remove anything from the
list because Mojo objects don't maintain their identity when you
transfer them through a message pipe. Now we just watch for errors on
the listener's pipe, which means the way you stop listening is just to
close your end of the pipe.

Add more rules to determine which overloaded Java method should be invoked
for a given Dart call.  In particular, check whether the class of a
Dart-wrapped Java object matches the type declared for the corresponding
argument in the Java method.

Firebase support for password authentication (on Android)

iOS: Always regenerate the precompilation snapshot when building for the device

iOS: Always rebuild the FLX file

iOS: Drain and pass URLRequest body data to the platform implementation

Dart/JNI: reflection-based wrapper for the raw JNI API

Switch whitespace mode back to pre-wrap

When we removed position: sticky, we introduced a subtle line breaking
bug to pre-wrap that would cause whitespace to accumulate at the
beginning of lines that follow unclean breaks. This patch adds back the
deleted code (cleansed of the position sticky bits).

rev engine

Use the same registration process as GCM for Firebase

Fix type of nested data structures on Android

Example:
  JavaClass dateFormatClass = Java.getClass('java.text.SimpleDateFormat');
  JavaObject format = dateFormatClass.newInstance('yyyy.MM.dd');
  print(format.parse('2016.01.01').getYear());

Android support for Firebase setValue

rev engine

Support dynamic registration of mojo services on Android

SkyApplication now reads service info from a services.json file bundled
with the apk. For each service, it registers a method that invokes
connectToService on a named class. This way, third party services can
register themselves.

There's a corresponding change to flutter_tools to generate this
services.json when building an apk that depends on services.

Improve handling of window insets on Android

Now that we understand window insets, we don't need to hard-code the size of
the status bar. Also, convert the viewport metrics to be consistently in
physical pixels.

A sound pool implementation for iOS