Fix this->window confusion in DevMode

dev/core/src/com/google/gwt/dev/shell/rewrite/RewriteJsniMethods.java

Index: dev/core/src/com/google/gwt/dev/shell/rewrite/RewriteJsniMethods.java
diff --git a/dev/core/src/com/google/gwt/dev/shell/rewrite/RewriteJsniMethods.java b/dev/core/src/com/google/gwt/dev/shell/rewrite/RewriteJsniMethods.java
index da8a029227f2db9c5f01c3712367e38ef563ceeb..9760f065983318463be7c88b864bf3ce3b02c9e3 100644
--- a/dev/core/src/com/google/gwt/dev/shell/rewrite/RewriteJsniMethods.java
+++ b/dev/core/src/com/google/gwt/dev/shell/rewrite/RewriteJsniMethods.java
@@ -255,6 +255,13 @@ public class RewriteJsniMethods extends ClassAdapter {
         visitInsn(Opcodes.ACONST_NULL);
       } else {
         loadThis();
+        // Ensure the instance method is not invoked against null, otherwise
+        // JS's apply will turn it into the window object. See Issue 3069.
+        visitMethodInsn(
+            Opcodes.INVOKESTATIC,
+            "com/google/gwt/dev/shell/JavaScriptHost",
+            "checkNotNull",
+            "(Ljava/lang/Object;)Ljava/lang/Object;");
       }
       // Stack is at 2