Add empty mapping entries for the ranges of generated JavaScript that don't map to any Dart source …

lib/compiler/implementation/code_buffer.dart

Index: lib/compiler/implementation/code_buffer.dart
diff --git a/lib/compiler/implementation/code_buffer.dart b/lib/compiler/implementation/code_buffer.dart
index 3c3053e429942e4cfa4f7018efbf1998d6576e7b..6a60bc2791548e09cd68e640462ace07fe440cf3 100644
--- a/lib/compiler/implementation/code_buffer.dart
+++ b/lib/compiler/implementation/code_buffer.dart
@@ -6,6 +6,7 @@ class CodeBuffer implements StringBuffer {
   StringBuffer buffer;
   List<SourceLocation> sourceLocations;
   int lastBufferOffset = 0;
+  int mappedRangeCounter = 0;
 
   CodeBuffer()
       : buffer = new StringBuffer(),
@@ -25,6 +26,9 @@ class CodeBuffer implements StringBuffer {
     if (object is CodeBuffer) {
       return addBuffer(object);
     }
+    if (mappedRangeCounter == 0) {

[floitsch, 2012/09/05 14:22:18]

one line.

[podivilov, 2012/09/06 10:52:25]

Done.

+      setSourceLocation(null, null);
+    }
     buffer.add(object.toString());
     return this;
   }
@@ -67,6 +71,15 @@ class CodeBuffer implements StringBuffer {
     return buffer.toString();
   }
 
+  void beginMappedRange() {
+    mappedRangeCounter += 1;

[floitsch, 2012/09/05 14:22:18]

++

[podivilov, 2012/09/06 10:52:25]

Done.

+  }
+
+  void endMappedRange() {
+    assert(mappedRangeCounter > 0);
+    mappedRangeCounter -= 1;

[floitsch, 2012/09/05 14:22:18]

--

[podivilov, 2012/09/06 10:52:25]

Done.

+  }
+
   void setSourceLocation(Element element, Token token) {
     int offsetDelta = buffer.length - lastBufferOffset;
     sourceLocations.add(new SourceLocation(element, token, offsetDelta));