Support full dart2js output for dartdoc/apidoc.

sdk/lib/_internal/dartdoc/bin/dartdoc.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * To generate docs for a library, run this script with the path to an
  * entrypoint .dart file, like:
  *
  *     $ dart dartdoc.dart foo.dart
  *
@@ skipping 214 matching lines @@
       var libDir = parts.lastIndexOf('lib');
       if (libDir > 0) {
         pkgPath = new Path(path.join(path.joinAll(parts.take(libDir - 1)),
               'packages'));
       }
     }
   }
 
   cleanOutputDirectory(dartdoc.outputDir);
 
-  dartdoc.documentLibraries(entrypoints, libPath, pkgPath);
+  print('Analyzing sources');
+  Future documented = dartdoc.documentLibraries(entrypoints, libPath, pkgPath);
 
-  Future compiled = compileScript(dartdoc.mode, dartdoc.outputDir, libPath);
-  Future filesCopied = copyDirectory(scriptDir.append('../static'),
-                                     dartdoc.outputDir);
+  documented.then((_) {
+    Future compiled = compileScript(dartdoc.mode, dartdoc.outputDir, libPath);
+    Future filesCopied = copyDirectory(scriptDir.append('../static'),
+                                       dartdoc.outputDir);
 
-  Future.wait([compiled, filesCopied]).then((futureStatus) {
+    Future.wait([compiled, filesCopied]).then((_) {
+      dartdoc.cleanup();
+      if (dartdoc.totalLibraries + dartdoc.totalTypes +
+          dartdoc.totalMembers == 0) {
+        print('Nothing was documented!');
+        exit(1);
+      } else {
+        print('Documented ${dartdoc.totalLibraries} libraries, '
+              '${dartdoc.totalTypes} types, and ${dartdoc.totalMembers} '
+              'members.');
+      }
+    });
+  }, onError: (AsyncError asyncError) {
+    print('Generation failed: ${asyncError.error}');
     dartdoc.cleanup();
-
-    if (dartdoc.totalLibraries + dartdoc.totalTypes +
-      dartdoc.totalMembers == 0) {
-      print('Nothing was documented!');
-      exit(1);
-    } else {
-      print('Documented ${dartdoc.totalLibraries} libraries, '
-            '${dartdoc.totalTypes} types, and ${dartdoc.totalMembers} '
-            'members.');
-    }
   });
 }