Fix DDC build

lib/src/compiler/compiler.dart

 // Copyright (c) 2016, 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:args/args.dart' show ArgParser, ArgResults;
 import 'package:analyzer/analyzer.dart'
     show AnalysisError, CompilationUnit, ErrorSeverity;
 import 'package:analyzer/src/generated/engine.dart' show AnalysisContext;
 import 'package:analyzer/src/generated/java_engine.dart' show AnalysisException;
 import 'package:analyzer/src/generated/source_io.dart' show Source, SourceKind;
@@ skipping 36 matching lines @@
   ///
   /// *Warning* - this may require resolving the entire world.
   /// If that is not desired, the analysis context must be pre-configured using
   /// summaries before calling this method.
   JSModuleFile compile(BuildUnit unit, CompilerOptions options) {
     var trees = <CompilationUnit>[];
     var errors = <AnalysisError>[];
 
     for (var sourcePath in unit.sources) {
       String sourceUri = sourcePath;
-      if (path.isRelative(sourcePath)) {
-        sourceUri = path.absolute(sourceUri);
+      if (path.isAbsolute(sourcePath)) {
+        sourceUri = path.toUri(sourcePath).toString();
       }
-      sourceUri = path.toUri(sourceUri).toString();
       Source source = context.sourceFactory.forUri(sourceUri);
       if (source == null) {
         throw new AnalysisException('could not create a source for $sourcePath.'
             ' The file name is in the wrong format or was not found.');
       }
 
       // Ignore parts. They need to be handled in the context of their library.
       if (context.getKindOf(source) == SourceKind.PART) {
         continue;
       }
@@ skipping 189 matching lines @@
 
     var map = new Map.from(this.sourceMap);
     List list = new List.from(map['sources']);
     map['sources'] = list;
     for (int i = 0; i < list.length; i++) {
       list[i] = path.relative(list[i], from: dir);
     }
     return map;
   }
 }