Various DDC fixes for windows

pkg/dev_compiler/lib/src/compiler/source_map_printer.dart

 // Copyright (c) 2015, 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.
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_resolution_map.dart';
 import 'package:source_maps/source_maps.dart' hide Printer;
 import 'package:source_span/source_span.dart' show SourceLocation;
 
 import '../js_ast/js_ast.dart' as JS;
@@ skipping 48 matching lines @@
           source.isInSystemLibrary ? source.uri.toString() : source.fullName;
     }
     // Skip MethodDeclarations - in the case of a one line function it finds the
     // declaration rather than the body and confuses devtools.
     if (node is MethodDeclaration) return;
     _mark(node.offset, _getIdentifier(node));
   }
 
   void exitNode(JS.Node jsNode) {
     AstNode node = jsNode.sourceInformation;
-    if (unit == null || node == null || node.offset == -1) return;
+    if (unit == null || node == null || node.offset == -1 || node.isSynthetic)
+      return;

[Jennifer Messerly, 2017/04/20 18:22:39]

I think this needs to be { ... } per style guide

BTW, now that you've added isSynthetic you might be able to remove `node.offset
== -1` ?

[vsm, 2017/04/20 18:29:05]

Done
I put that in to match the enterNode above.  Can we remove both?

 
     // TODO(jmesserly): in many cases marking the end will be unnecessary.
     // Skip MethodDeclarations - in the case of a one line function it finds the
     // declaration rather than the body and confuses devtools.
     if (node is! MethodDeclaration) {
       _mark(node.end);
     }
 
     if (identical(node, _currentTopLevelDeclaration)) {
       unit = null;
       sourcePath = null;
       _currentTopLevelDeclaration == null;
     }
   }
 
   // TODO(jmesserly): prefix identifiers too, if they map to a named element.
   String _getIdentifier(AstNode node) =>
       node is SimpleIdentifier ? node.name : null;
 
   void _mark(int offset, [String identifier]) {
     var loc = unit.lineInfo.getLocation(offset);
     // Chrome Devtools wants a mapping for the beginning of
     // a line, so bump locations at the end of a line to the beginning of
     // the next line.
     var next = unit.lineInfo.getLocation(offset + 1);
     if (next.lineNumber == loc.lineNumber + 1) {
       loc = next;
     }
+    var sourceUrl =
+        sourcePath.startsWith('dart:') || sourcePath.startsWith('package:')
+            ? sourcePath
+            : new Uri.file(sourcePath);
     sourceMap.addLocation(
         new SourceLocation(offset,
-            sourceUrl: sourcePath,
+            sourceUrl: sourceUrl,
             line: loc.lineNumber - 1,
             column: loc.columnNumber - 1),
         new SourceLocation(buffer.length, line: _line, column: _column),
         identifier);
   }
 }
 
 const int _LF = 10;
 const int _CR = 13;