Workaround for broken travis (#1597)

* Workaround for broken travis

* fix dependency on correct path setting

Author: jcollins-g

lib/src/io_utils.dart

@@ -91,7 +91,11 @@ class SubprocessLauncher {
   }
 
   SubprocessLauncher(this.context, [Map<String, String> environment]) {
-    if (environment == null) this._environment = new Map();
+    if (environment == null) {
+      this._environment = new Map();
+    } else {
+      this._environment = environment;
+    }
   }
 
   /// A wrapper around start/await process.exitCode that will display the

tool/grind.dart

@@ -242,11 +242,13 @@ Future buildFlutterDocs() async {
 }
 
 Future _buildFlutterDocs(String flutterPath, [String label]) async {
+  Map<String, String> env = _createThrowawayPubCache();
+  env['PATH'] = '${path.join(flutterPath, "bin")}:${env['PATH']}';
   var launcher = new SubprocessLauncher(
       'build-flutter-docs${label == null ? "" : "-$label"}',
-      _createThrowawayPubCache());
+      env);
   await launcher.runStreamed('git',
-      ['clone', '--depth', '1', 'https://github.com/flutter/flutter.git', '.'],
+      ['clone', 'https://github.com/flutter/flutter.git', '.'],
       workingDirectory: flutterPath);
   String flutterBin = path.join('bin', 'flutter');
   String flutterCacheDart =