Warn user if DART_SDK does not match editor SDK

editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/sdk/DirectoryBasedDartSdk.java

Index: editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/sdk/DirectoryBasedDartSdk.java
diff --git a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/sdk/DirectoryBasedDartSdk.java b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/sdk/DirectoryBasedDartSdk.java
index efed04c2c104f9bda5de95462cd27ef116a74508..fe0b98c1f9ca0fea0be49268e8da4207361b8311 100644
--- a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/sdk/DirectoryBasedDartSdk.java
+++ b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/sdk/DirectoryBasedDartSdk.java
@@ -83,7 +83,7 @@ public class DirectoryBasedDartSdk implements DartSdk {
   /**
    * The name of the environment variable whose value is the path to the default Dart SDK directory.
    */
-  private static final String DART_SDK_ENVIRONMENT_VARIABLE_NAME = "DART_SDK"; //$NON-NLS-1$
+  public static final String DART_SDK_ENVIRONMENT_VARIABLE_NAME = "DART_SDK"; //$NON-NLS-1$
 
   /**
    * The name of the file containing the Dartium executable on Linux.
@@ -173,22 +173,6 @@ public class DirectoryBasedDartSdk implements DartSdk {
   }
 
   /**
-   * Return the default Dart SDK, or {@code null} if the directory containing the default SDK cannot
-   * be determined (or does not exist).
-   * <p>
-   * Added in order to test AnalysisContextImpl2.
-   * 
-   * @return the default Dart SDK
-   */
-  public static DirectoryBasedDartSdk getDefaultSdk2() {
-    File sdkDirectory = getDefaultSdkDirectory();
-    if (sdkDirectory == null) {
-      return null;
-    }
-    return new DirectoryBasedDartSdk(sdkDirectory, true);
-  }
-
-  /**
    * Return the default directory for the Dart SDK, or {@code null} if the directory cannot be
    * determined (or does not exist). The default directory is provided by a {@link System} property
    * named {@code com.google.dart.sdk}, or, if the property is not defined, an environment variable