Add a MathFloor stub generated with TurboFan

src/runtime.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This files contains runtime support implemented in JavaScript.
 
 // CAUTION: Some of the functions specified in this file are called
 // directly from compiled code. These are the functions with names in
 // ALL CAPS. The compiled code passes the first argument in 'this'.
 
@@ skipping 878 matching lines @@
 // that is cloned when running the code.  It is essential that the
 // boilerplate gets the right prototype.
 %FunctionSetPrototype($Array, new $Array(0));
 
 
 /* -----------------------------------------------
    - - -   J a v a S c r i p t   S t u b s   - - -
    -----------------------------------------------
 */
 
-function STRING_LENGTH_STUB(name) {
-  var receiver = this;  // implicit first parameter
+function StringLengthTF_STUB(receiver, name) {
   return %_StringGetLength(%_JSValueGetValue(receiver));
 }
+
+function MathFloor_STUB(f, i, v) {
+  var r = %_MathFloor(+v);
+  if (%_IsMinusZero(r)) {
+    %_FixedArraySet(%_GetTypeFeedbackVector(f), ((i|0)+1)|0, 1);

[Benedikt Meurer, 2015/05/11 04:40:12]

Please add a comment explaining what this line does. 

[danno, 2015/05/11 06:14:19]

Done.

+    return -0;
+  }
+  // Return integers in smi range as smis.
+  var trunc = r|0;
+  if (trunc === r) {
+    return trunc;
+  }
+  return r;
+}