Let printError be able to print bold also (#9714)

* Let printError print bold as well

* review notes

packages/flutter_tools/lib/src/android/android_device.dart

@@ -160,7 +160,7 @@ class AndroidDevice extends Device {
         return true;
       printError('The ADB at "${getAdbPath(androidSdk)}" is too old; please install version 1.0.32 or later.');
     } catch (error, trace) {
-      printError('Error running ADB: $error', trace);
+      printError('Error running ADB: $error', stackTrace: trace);
     }
 
     return false;

packages/flutter_tools/lib/src/application_package.dart

@@ -155,7 +155,7 @@ abstract class IOSApp extends ApplicationPackage {
       final Directory payloadDir = fs.directory(fs.path.join(tempDir.path, 'Payload'));
       bundleDir = payloadDir.listSync().singleWhere(_isBundleDirectory);
     } on StateError catch (e, stackTrace) {
-      printError('Invalid prebuilt iOS binary: ${e.toString()}', stackTrace);
+      printError('Invalid prebuilt iOS binary: ${e.toString()}', stackTrace: stackTrace);
       return null;
     }
 

packages/flutter_tools/lib/src/base/logger.dart

@@ -25,7 +25,7 @@ abstract class Logger {
 
   /// Display an error level message to the user. Commands should use this if they
   /// fail in some way.
-  void printError(String message, [StackTrace stackTrace]);
+  void printError(String message, { StackTrace stackTrace, bool emphasis: false });
 
   /// Display normal output of the command. This should be used for things like
   /// progress messages, success messages, or just normal command output.
@@ -60,10 +60,12 @@ class StdoutLogger extends Logger {
   bool get isVerbose => false;
 
   @override
-  void printError(String message, [StackTrace stackTrace]) {
+  void printError(String message, { StackTrace stackTrace, bool emphasis: false }) {
     _status?.cancel();
     _status = null;
 
+    if (emphasis)
+      message = terminal.bolden(message);
     stderr.writeln(message);
     if (stackTrace != null)
       stderr.writeln(stackTrace.toString());
@@ -144,7 +146,10 @@ class BufferLogger extends Logger {
   String get traceText => _trace.toString();
 
   @override
-  void printError(String message, [StackTrace stackTrace]) => _error.writeln(message);
+  void printError(String message, { StackTrace stackTrace, bool emphasis: false }) {
+    _error.writeln(message);
+  }
+
 
   @override
   void printStatus(
@@ -185,7 +190,7 @@ class VerboseLogger extends Logger {
   bool get isVerbose => true;
 
   @override
-  void printError(String message, [StackTrace stackTrace]) {
+  void printError(String message, { StackTrace stackTrace, bool emphasis: false }) {
     _emit(_LogType.error, message, stackTrace);
   }
 

packages/flutter_tools/lib/src/commands/daemon.dart

@@ -66,7 +66,7 @@ class DaemonCommand extends FlutterCommand {
   }
 
   dynamic _handleError(dynamic error, StackTrace stackTrace) {
-    printError('Error from flutter daemon: $error', stackTrace);
+    printError('Error from flutter daemon: $error', stackTrace: stackTrace);
     return null;
   }
 }
@@ -690,7 +690,7 @@ class NotifyingLogger extends Logger {
   Stream<LogMessage> get onMessage => _messageController.stream;
 
   @override
-  void printError(String message, [StackTrace stackTrace]) {
+  void printError(String message, { StackTrace stackTrace, bool emphasis: false }) {
     _messageController.add(new LogMessage('error', message, stackTrace));
   }
 
@@ -757,7 +757,7 @@ class _AppRunLogger extends Logger {
   int _nextProgressId = 0;
 
   @override
-  void printError(String message, [StackTrace stackTrace]) {
+  void printError(String message, { StackTrace stackTrace, bool emphasis: false }) {
     if (logToStdout) {
       stderr.writeln(message);
       if (stackTrace != null)

packages/flutter_tools/lib/src/globals.dart

@@ -15,7 +15,11 @@ Artifacts get artifacts => Artifacts.instance;
 
 /// Display an error level message to the user. Commands should use this if they
 /// fail in some way.
-void printError(String message, [StackTrace stackTrace]) => logger.printError(message, stackTrace);
+///
+/// Set `emphasis` to true to make the output bold if it's supported.
+void printError(String message, { StackTrace stackTrace, bool emphasis: false }) {
+  logger.printError(message, stackTrace: stackTrace, emphasis: emphasis);
+}
 
 /// Display normal output of the command. This should be used for things like
 /// progress messages, success messages, or just normal command output.