set package root after creating configuration, since defualt compiler configuration is used by an...

compiler/java/com/google/dart/compiler/DartCompiler.java

Index: compiler/java/com/google/dart/compiler/DartCompiler.java
===================================================================
--- compiler/java/com/google/dart/compiler/DartCompiler.java	(revision 10059)
+++ compiler/java/com/google/dart/compiler/DartCompiler.java	(working copy)
@@ -55,6 +55,7 @@
 import java.io.Writer;
 import java.net.URI;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
@@ -1029,6 +1030,7 @@
     }
 
     CompilerConfiguration config = new DefaultCompilerConfiguration(compilerOptions);
+    config.getSystemLibraryManager().setPackageRoots(Arrays.asList(new File[]{compilerOptions.getPackageRoot()}));
     return compilerMain(sourceFile, config);
   }