fix(dart/transform): Gracefully handle log calls before init

- Lazily create and use a logger that prints instead of `throw`ing.
- Use this logger in unit tests.

modules/angular2/src/transform/common/logging.dart

@@ -18,7 +18,37 @@ void setLogger(BuildLogger logger) {
 /// The logger the transformer should use for messaging.
 BuildLogger get logger {
   if (_logger == null) {
-    throw new StateError('Logger never initialized.');
+    _logger = new PrintLogger();
   }
   return _logger;
 }
+
+class PrintLogger implements BuildLogger {
+  void _printWithPrefix(prefix, msg) => print('$prefix: $msg');
+  void info(msg, {AssetId asset, SourceSpan span}) =>
+      _printWithPrefix('INFO', msg);
+  void fine(msg, {AssetId asset, SourceSpan span}) =>
+      _printWithPrefix('FINE', msg);
+  void warning(msg, {AssetId asset, SourceSpan span}) =>
+      _printWithPrefix('WARN', msg);
+  void error(msg, {AssetId asset, SourceSpan span}) {
+    throw new PrintLoggerError(msg, asset, span);
+  }
+  Future writeOutput() => null;
+  Future addLogFilesFromAsset(AssetId id, [int nextNumber = 1]) => null;
+}
+
+class PrintLoggerError extends Error {
+  final String message;
+  final AssetId asset;
+  final SourceSpan span;
+
+  PrintLoggerError(message, asset, span);
+
+  @override
+  String toString() {
+    return 'Message: ${Error.safeToString(message)}, '
+        'Asset: ${Error.safeToString(asset)}, '
+        'Span: ${Error.safeToString(span)}.';
+  }
+}