Add Array.prototype.includes

src/runtime.js

Index: src/runtime.js
diff --git a/src/runtime.js b/src/runtime.js
index c9cf825038a95ab642808b5ea027553e3b514b35..4bc377c5f063aa60924358ac7bbfb9ca45ba8d23 100644
--- a/src/runtime.js
+++ b/src/runtime.js
@@ -601,6 +601,15 @@ function SameValue(x, y) {
   return x === y;
 }
 
+// ES6, section 7.2.4
+function SameValueZero(x, y) {
+  if (typeof x != typeof y) return false;
+  if (IS_NUMBER(x)) {
+    if (NUMBER_IS_NAN(x) && NUMBER_IS_NAN(y)) return true;
+  }
+  return x === y;
+}
+
 
 /* ---------------------------------
    - - -   U t i l i t i e s   - - -