Implement correct scoping rules for variables.

pkg/analyzer_experimental/lib/src/services/formatter_impl.dart

Index: pkg/analyzer_experimental/lib/src/services/formatter_impl.dart
diff --git a/pkg/analyzer_experimental/lib/src/services/formatter_impl.dart b/pkg/analyzer_experimental/lib/src/services/formatter_impl.dart
index 032d5e768e71e413d00e22ee0f81e1879106d3fb..aeb1ba4fca76f7f57b4ea605a0c241917360fe2e 100644
--- a/pkg/analyzer_experimental/lib/src/services/formatter_impl.dart
+++ b/pkg/analyzer_experimental/lib/src/services/formatter_impl.dart
@@ -1294,11 +1294,11 @@ class SourceVisitor implements ASTVisitor {
     var lines = max(min, countNewlinesBetween(previousToken, currentToken));
     writer.newlines(lines);
 
-    var previousToken = currentToken.previous;
+    var newPreviousToken = currentToken.previous;
 
     while (comment != null) {
 
-      emitComment(comment, previousToken);
+      emitComment(comment, newPreviousToken);
 
       var nextToken = comment.next != null ? comment.next : token;
       var newlines = calculateNewlinesBetweenComments(comment, nextToken);
@@ -1309,11 +1309,11 @@ class SourceVisitor implements ASTVisitor {
         space();
       }
 
-      previousToken = comment;
+      newPreviousToken = comment;
       comment = comment.next;
     }
 
-    previousToken = token;

[karlklose, 2013/09/26 07:05:43]

@pquitslund: This looks like a bug.

[ngeoffray, 2013/09/26 07:48:38]

Why did you have to fix it? Isn't it OK to shadow a field?

[pquitslund, 2013/09/30 16:12:48]

Hmmm, I agree this doesn't look right.  I have another proposed fix though. 
Let's just remove the variable declaration for 'previousToken'.  I don't think I
intended to be shadowing here but I do think I want the side-effect of updating
the cached previous.  (Although, that may benefit from a rethink too.)

[pquitslund, 2013/09/30 17:23:34]

And here's that fix: https://codereview.chromium.org/25304002/

+    newPreviousToken = token;
     return lines;
   }