Add no-info mappings at start of out.js and after mapped functions

pkg/compiler/lib/src/io/source_map_builder.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.
 
 library dart2js.source_map_builder;
 
 import '../util/uri_extras.dart' show relativize;
 import '../util/util.dart';
 import 'line_column_provider.dart';
 import 'source_information.dart' show SourceLocation;
@@ skipping 34 matching lines @@
     Map<Uri, LineColumnMap<SourceMapEntry>> sourceLocationMap =
         <Uri, LineColumnMap<SourceMapEntry>>{};
     entries.forEach((SourceMapEntry sourceMapEntry) {
       int line = lineColumnProvider.getLine(sourceMapEntry.targetOffset);
       int column =
           lineColumnProvider.getColumn(line, sourceMapEntry.targetOffset);
       lineColumnMap.add(line, column, sourceMapEntry);
 
       SourceLocation location = sourceMapEntry.sourceLocation;
       if (location != null) {
-        LineColumnMap<SourceMapEntry> sourceLineColumnMap =
-            sourceLocationMap.putIfAbsent(
-                location.sourceUri, () => new LineColumnMap<SourceMapEntry>());
-        sourceLineColumnMap.add(location.line, location.column, sourceMapEntry);
+        if (location.sourceUri != null) {
+          LineColumnMap<SourceMapEntry> sourceLineColumnMap =
+              sourceLocationMap.putIfAbsent(location.sourceUri,
+                  () => new LineColumnMap<SourceMapEntry>());
+          sourceLineColumnMap.add(
+              location.line, location.column, sourceMapEntry);
+        }
       }
     });
 
     return _build(lineColumnMap);
   }
 
   String _build(LineColumnMap<SourceMapEntry> lineColumnMap) {
     IndexMap<Uri> uriMap = new IndexMap<Uri>();
     IndexMap<String> nameMap = new IndexMap<String>();
 
     lineColumnMap.forEachElement((SourceMapEntry entry) {
       SourceLocation sourceLocation = entry.sourceLocation;
       if (sourceLocation != null) {
-        uriMap.register(sourceLocation.sourceUri);
-        if (sourceLocation.sourceName != null) {
-          nameMap.register(sourceLocation.sourceName);
+        if (sourceLocation.sourceUri != null) {
+          uriMap.register(sourceLocation.sourceUri);
+          if (sourceLocation.sourceName != null) {
+            nameMap.register(sourceLocation.sourceName);
+          }
         }
       }
     });
 
     StringBuffer mappingsBuffer = new StringBuffer();
     writeEntries(lineColumnMap, uriMap, nameMap, mappingsBuffer);
 
     StringBuffer buffer = new StringBuffer();
     buffer.write('{\n');
     buffer.write('  "version": 3,\n');
@@ skipping 51 matching lines @@
       }
       firstEntryInLine = false;
 
       targetColumnEncoder.encode(output, targetColumn);
 
       if (sourceLocation == null) {
         return;
       }
 
       Uri sourceUri = sourceLocation.sourceUri;
-      sourceUriIndexEncoder.encode(output, uriMap[sourceUri]);
-      sourceLineEncoder.encode(output, sourceLocation.line);
-      sourceColumnEncoder.encode(output, sourceLocation.column);
+      if (sourceUri != null) {
+        sourceUriIndexEncoder.encode(output, uriMap[sourceUri]);
+        sourceLineEncoder.encode(output, sourceLocation.line);
+        sourceColumnEncoder.encode(output, sourceLocation.column);
+      }
 
       String sourceName = sourceLocation.sourceName;
       if (sourceName != null) {
         sourceNameIndexEncoder.encode(output, nameMap[sourceName]);
       }
 
       previousSourceLocation = sourceLocation;
     });
   }
 }
@@ skipping 132 matching lines @@
   int register(T element) {
     return map.putIfAbsent(element, () => map.length);
   }
 
   /// Returns the index of [element].
   int operator [](T element) => map[element];
 
   /// Returns the indexed elements.
   Iterable<T> get elements => map.keys;
 }