Dev compiler debugger related tweaks.

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 31 matching lines @@
 
   void enterNode(JS.Node jsNode) {
     AstNode node = jsNode.sourceInformation;
     if (node == null || node.offset == -1 || node.isSynthetic) return;
     if (unit == null) {
       // This is a top-level declaration.  Note: consecutive top-level
       // declarations may come from different compilation units due to
       // parts.
       _currentTopLevelDeclaration = node;
       unit = node.getAncestor((n) => n is CompilationUnit);
+      var source = resolutionMap.elementDeclaredByCompilationUnit(unit).source;
+      // Use the uri for dart: uris instead of the path of the source file
+      // on disk as that results in much cleaner stack traces.
+      // Example:
+      // source.uri = dart:core/object.dart
+      // source.fullName = gen/patched_sdk/lib/core/object.dart
       sourcePath =
-          resolutionMap.elementDeclaredByCompilationUnit(unit).source.fullName;
+          source.isInSystemLibrary ? source.uri.toString() : source.fullName;
     }

[Jacob, 2017/04/15 02:26:49]

Jenny please review this change. This switches to showing dart: uris for all
system library files instead
of the confusing paths to their locations in the gen directory.

[Jennifer Messerly, 2017/04/17 21:37:05]

Nice!!!

     // 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;
 
@@ skipping 29 matching lines @@
             sourceUrl: sourcePath,
             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;