Manager.emitAll() implementation will expose a compiling issue on dart2js

[jumperchen]

According to this issue dart-lang/sdk#31149
we should change the implementation of this line -

socket.io-client-dart/lib/src/manager.dart

Line 97 in 73adbcf

Function.apply(this.emit, [event, data]);

by using this.emit(event, data); to avoid dart2js issue.