Make Dart_ScriptGetTokenInfo account for line_offset() and col_offset()

tools/coverage.dart

 // Copyright (c) 2013, 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.
 
 // This test forks a second vm process that runs a dart script as
 // a debug target, single stepping through the entire program, and
 // recording each breakpoint. At the end, a coverage map of the source
 // is printed.
 //
 // Usage: dart coverage.dart [--wire] [--verbose] target_script.dart
@@ skipping 60 matching lines @@
 
   Source(this.url);
 
   void recordBp(int tokenPos) {
     var count = tokenCounts[tokenPos];
     tokenCounts[tokenPos] = count == null ? 1 : count + 1;
   }
 
   void SetLineInfo(List lineInfoTable) {
     // Each line is encoded as an array with first element being the line
-    // number, followed by pairs of (tokenPosition, textOffset).
+    // number, followed by pairs of (tokenPosition, columnNumber).
     lineInfoTable.forEach((List<int> line) {
       int lineNumber = line[0];
       for (int t = 1; t < line.length; t += 2) {
         assert(tokenPosToLine[line[t]] == null);
         tokenPosToLine[line[t]] = lineNumber;
       }
     });
   }
 
   // Print out the annotated source code. For each line that has seen
@@ skipping 446 matching lines @@
         targetOpts.add(str);
         break;
     }
   }
 
   Process.start(options.executable, targetOpts).then((Process process) {
     process.stdin.close();
     debugger = new Debugger(process);
   });
 }