Blink-in-JS: Support private scripts in partial interfaces (PrivateScriptRunner part)

Source/bindings/core/v8/PrivateScriptRunner.js

Index: Source/bindings/core/v8/PrivateScriptRunner.js
diff --git a/Source/bindings/core/v8/PrivateScriptRunner.js b/Source/bindings/core/v8/PrivateScriptRunner.js
index 0baab26b2ba49017ea9b8f826d860d8373e6c17c..75c7e9bd2d6bf32d9435f2996207e23496ae7ba1 100644
--- a/Source/bindings/core/v8/PrivateScriptRunner.js
+++ b/Source/bindings/core/v8/PrivateScriptRunner.js
@@ -82,7 +82,8 @@ function privateScriptClass()
 
 function installClass(className, implementation)
 {
-    installedClasses[className] = new privateScriptClass();
+    if (installedClasses[className] === undefined)
+        installedClasses[className] = new privateScriptClass();
     implementation(window, installedClasses[className]);
 }