Implement ReadableStream as a V8 extra

Source/core/streams/CountQueuingStrategy.js

Index: Source/core/streams/CountQueuingStrategy.js
diff --git a/Source/core/streams/CountQueuingStrategy.js b/Source/core/streams/CountQueuingStrategy.js
new file mode 100644
index 0000000000000000000000000000000000000000..f4532b395e8b4cf0e8128e1c5964061fe1f3fdd1
--- /dev/null
+++ b/Source/core/streams/CountQueuingStrategy.js
@@ -0,0 +1,18 @@
+(function() {
+    'use strict';
+
+    const NONE = 0;
+    const DONT_ENUM = 2;
+
+    class CountQueuingStrategy {
+        constructor(options) {
+            %AddNamedProperty(this, 'highWaterMark', options.highWaterMark, NONE);
+        }
+
+        size(chunk) {
+            return 1;
+        }
+    }
+
+    %AddNamedProperty(global, 'CountQueuingStrategy', CountQueuingStrategy, DONT_ENUM);
+});