Add additional hints to the analyzer to catch the 'x is double' dart2js bug.

editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/DartCore.java

Index: editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/DartCore.java
diff --git a/editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/DartCore.java b/editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/DartCore.java
index f3b9a23f30cb871a0ba480336c3481a79be9048d..9b5f52fbbf1d60ea59e692951a7541da73da4323 100644
--- a/editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/DartCore.java
+++ b/editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/DartCore.java
@@ -151,15 +151,20 @@ public class DartCore extends Plugin implements DartSdkListener {
   public static final String EXTENSION_JS = "js";
 
   /**
-   * Preference for the automatically running pub
+   * Preference for the automatically running pub.
    */
   public static final String PUB_AUTO_RUN_PREFERENCE = "pubAutoRun";
 
   /**
-   * Preference for enabling hints
+   * Preference for enabling hints.
    */
   public static final String ENABLE_HINTS_PREFERENCE = "enableHints";
 
+  /**
+   * Preference for enabling dart2js related hints.
+   */
+  public static final String ENABLE_HINTS_DART2JS_PREFERENCE = "enableHints_dart2js";
+
   public static final String PROJECT_PREF_PACKAGE_ROOT = "projectPackageRoot";
 
   /**
@@ -1393,6 +1398,10 @@ public class DartCore extends Plugin implements DartSdkListener {
     return DartCore.getPlugin().getPrefs().getBoolean(PUB_AUTO_RUN_PREFERENCE, true);
   }
 
+  public boolean isHintsDart2JSEnabled() {
+    return DartCore.getPlugin().getPrefs().getBoolean(ENABLE_HINTS_DART2JS_PREFERENCE, true);
+  }
+
   public boolean isHintsEnabled() {
     return DartCore.getPlugin().getPrefs().getBoolean(ENABLE_HINTS_PREFERENCE, true);
   }