Add a MathFloor stub generated with TurboFan

src/runtime.js

Index: src/runtime.js
diff --git a/src/runtime.js b/src/runtime.js
index 5e7e956c22a7b96458a308e44d48d1fe0ce2b511..7fab3cace4fc887d819a72508f1e39b25aa08284 100644
--- a/src/runtime.js
+++ b/src/runtime.js
@@ -62,7 +62,8 @@ var TO_NUMBER;
 var TO_STRING;
 var TO_NAME;
 
-var STRING_LENGTH_STUB;
+var StringLengthTF_STUB;
+var MathFloor_STUB;
 
 var $defaultNumber;
 var $defaultString;
@@ -750,11 +751,31 @@ TO_NAME = function TO_NAME() {
    -----------------------------------------------
 */
 
-STRING_LENGTH_STUB = function STRING_LENGTH_STUB(name) {
-  var receiver = this;  // implicit first parameter
+StringLengthTF_STUB = function StringLengthTF_STUB(receiver, name) {
   return %_StringGetLength(%_JSValueGetValue(receiver));
 }
 
+MathFloor_STUB = function MathFloor_STUB(f, i, v) {
+  // |f| is calling function's JSFunction
+  // |i| is TypeFeedbackVector slot # of callee's CallIC for Math.floor call
+  // |v| is the value to floor
+  var r = %_MathFloor(+v);
+  if (%_IsMinusZero(r)) {
+    // Collect type feedback when the result of the floor is -0. This is
+    // accomplished by storing a sentinel in the second, "extra"
+    // TypeFeedbackVector slot corresponding to the Math.floor CallIC call in
+    // the caller's TypeVector.
+    %_FixedArraySet(%_GetTypeFeedbackVector(f), ((i|0)+1)|0, 1);
+    return -0;
+  }
+  // Return integers in smi range as smis.
+  var trunc = r|0;
+  if (trunc === r) {
+    return trunc;
+  }
+  return r;
+}
+
 
 /* -------------------------------------
    - - -   C o n v e r s i o n s   - - -