Bold each line individually (#9069)

This should make the message in Travis logs look better.

packages/flutter_tools/lib/executable.dart

@@ -294,7 +294,7 @@ Future<String> _doctorText() async {
 
 Future<int> _exit(int code) async {
   if (flutterUsage.isFirstRun)
-    flutterUsage.printUsage();
+    flutterUsage.printWelcome();
 
   // Send any last analytics calls that are in progress without overly delaying
   // the tool's exit (we wait a maximum of 250ms).

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

@@ -277,14 +277,22 @@ class AnsiTerminal {
 
   bool supportsColor;
 
-  String bolden(String str) => supportsColor ? '$_bold$str$_reset' : str;
+  String bolden(String message) {
+    if (!supportsColor)
+      return message;
+    final StringBuffer result = new StringBuffer();
+    for (String line in message.split('\n'))
+      result.writeln('$_bold$line$_reset');
+    return result.toString();
+  }
 
   String clearScreen() => supportsColor ? _clear : '\n\n';
 
   set singleCharMode(bool value) {
-    // TODO(goderbauer): instead of trying to set lineMode and then catching [_ENOTTY] or [_INVALID_HANDLE],
-    //     we should check beforehand if stdin is connected to a terminal or not
-    //     (requires https://github.com/dart-lang/sdk/issues/29083 to be resolved).
+    // TODO(goderbauer): instead of trying to set lineMode and then catching
+    // [_ENOTTY] or [_INVALID_HANDLE], we should check beforehand if stdin is
+    // connected to a terminal or not.
+    // (Requires https://github.com/dart-lang/sdk/issues/29083 to be resolved.)
     try {
       // The order of setting lineMode and echoMode is important on Windows.
       if (value) {

packages/flutter_tools/lib/src/runner/flutter_command.dart

@@ -116,7 +116,7 @@ abstract class FlutterCommand extends Command<Null> {
     final UsageTimer analyticsTimer = usagePath == null ? null : flutterUsage.startTimer(name);
 
     if (flutterUsage.isFirstRun)
-      flutterUsage.printUsage();
+      flutterUsage.printWelcome();
 
     return verifyThenRunCommand().whenComplete(() {
       final int ms = stopwatch.elapsedMilliseconds;

packages/flutter_tools/lib/src/usage.dart

@@ -47,7 +47,7 @@ class Usage {
 
   Analytics _analytics;
 
-  bool _printedUsage = false;
+  bool _printedWelcome = false;
   bool _suppressAnalytics = false;
 
   bool get isFirstRun => _analytics.firstRun;
@@ -108,10 +108,12 @@ class Usage {
     await _analytics.waitForLastPing(timeout: const Duration(milliseconds: 250));
   }
 
-  void printUsage() {
-    if (_printedUsage)
+  void printWelcome() {
+    // This gets called if it's the first run by the selected command, if any,
+    // and on exit, in case there was no command.
+    if (_printedWelcome)
       return;
-    _printedUsage = true;
+    _printedWelcome = true;
 
     printStatus('');
     printStatus('''

packages/flutter_tools/test/src/context.dart

@@ -218,7 +218,7 @@ class MockUsage implements Usage {
   Future<Null> ensureAnalyticsSent() => new Future<Null>.value();
 
   @override
-  void printUsage() { }
+  void printWelcome() { }
 }
 
 class _MockUsageTimer implements UsageTimer {