add support for package: to the editor

compiler/java/com/google/dart/compiler/CommandLineOptions.java

Index: compiler/java/com/google/dart/compiler/CommandLineOptions.java
===================================================================
--- compiler/java/com/google/dart/compiler/CommandLineOptions.java	(revision 7713)
+++ compiler/java/com/google/dart/compiler/CommandLineOptions.java	(working copy)
@@ -103,6 +103,10 @@
         usage = "Path to dart sdk.  (system property com.google.dart.sdk)")
     private File dartSdkPath = SystemLibraryManager.DEFAULT_SDK_PATH;
     
+    @Option(name = "--package-root",
+        usage = "Root directory used for the package: scheme")
+    private File packageRoot = SystemLibraryManager.DEFAULT_PACKAGE_ROOT;
+    
     @Option(name = "--show-sdk-warnings", usage = "show warnings from SDK source")
     private boolean showSdkWarnings = false;
     
@@ -135,6 +139,13 @@
       return platformName;
     }
 
+    /**
+     * @return the packageRoot
+     */
+    public File getPackageRoot() {
+      return packageRoot;
+    }
+
     public File getDartSdkPath() {
       return dartSdkPath;
     }