Add methods for creating V8 extras-based ReadableStreams from C++

third_party/WebKit/Source/core/streams/CountQueuingStrategy.js

Index: third_party/WebKit/Source/core/streams/CountQueuingStrategy.js
diff --git a/third_party/WebKit/Source/core/streams/CountQueuingStrategy.js b/third_party/WebKit/Source/core/streams/CountQueuingStrategy.js
index 61567c899512697bcc2a8ce65b931282974f0661..36141b74d34b905f05c91f912c67cd2ffc93b22b 100644
--- a/third_party/WebKit/Source/core/streams/CountQueuingStrategy.js
+++ b/third_party/WebKit/Source/core/streams/CountQueuingStrategy.js
@@ -16,6 +16,7 @@
         writable: true
       });
     }
+
     size(chunk) { return 1; }
   }
 
@@ -25,4 +26,17 @@
     configurable: true,
     writable: true
   });
+
+  // Export a separate copy that doesn't need options objects and can't be
+  // interfered with.
+  class BuiltInCountQueuingStrategy {
+    constructor(highWaterMark) {
+      defineProperty(this, 'highWaterMark', {value: highWaterMark});
+    }
+
+    size(chunk) { return 1; }
+  }
+
+  binding.createBuiltInCountQueuingStrategy = highWaterMark =>
+      new BuiltInCountQueuingStrategy(highWaterMark);
 });