Add a command-line option for generating source maps.

compiler/java/com/google/dart/runner/DartRunner.java

 // Copyright (c) 2011, 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.
 
 package com.google.dart.runner;
 
 import com.google.common.base.Joiner;
 import com.google.common.collect.Lists;
 import com.google.common.io.CharStreams;
 import com.google.common.io.Files;
@@ skipping 355 matching lines @@
                                               DartCompilerListener listener) throws RunnerError {
     try {
       final RunnerDartArtifactProvider provider = new RunnerDartArtifactProvider();
       String errmsg = DartCompiler.compileLib(app, imports, config, provider, listener);
       if (errmsg != null) {
          throw new RunnerError(errmsg);
       }
       Backend backend = config.getBackends().get(0);
 
       SourceMapping mapping = null;
-      Reader mr = provider.getArtifactReader(app, "", backend.getSourceMapExtension());
-      if (mr != null) {
-        String mapContents = CharStreams.toString(mr);
-        try {
-          mapping = SourceMapConsumerFactory.parse(mapContents, new SourceMapSupplier() {
+      if (config.getCompilerOptions().generateSourceMaps()) {
+        Reader mr = provider.getArtifactReader(app, "", backend.getSourceMapExtension());
+        if (mr != null) {
+          String mapContents = CharStreams.toString(mr);
+          try {
+            mapping = SourceMapConsumerFactory.parse(mapContents, new SourceMapSupplier() {
 
-            @Override
-            public String getSourceMap(String url) {
-              String contents = provider.getGeneratedFileContents(url);
-              if (contents == null || contents.isEmpty()) {
-                return null;
+              @Override
+              public String getSourceMap(String url) {
+                String contents = provider.getGeneratedFileContents(url);
+                if (contents == null || contents.isEmpty()) {
+                  return null;
+                }
+                return contents;
               }
-              return contents;
-            }
 
-          });
-        } catch (SourceMapParseException e) {
-          throw new AssertionError(e);
+            });
+          } catch (SourceMapParseException e) {
+            throw new AssertionError(e);
+          }
+          mr.close();
         }
-        mr.close();
       }
 
       Reader r = provider.getArtifactReader(app, "", backend.getAppExtension());
       String js = CharStreams.toString(r);
       r.close();
       return new CompilationResult(js, mapping);
     } catch (IOException e) {
       // This can't happen; it's just a StringWriter.
       throw new AssertionError(e);
     }
   }
 }