[turbofan] Unify Math.floor / Math.ceil optimization.

src/math.js

Index: src/math.js
diff --git a/src/math.js b/src/math.js
index 2da38779e7cc31a1f7fcd29c9c83e83f1cbdb7cd..83bca9348efd6294b5e606f2a4f8655ec8471e1b 100644
--- a/src/math.js
+++ b/src/math.js
@@ -57,7 +57,7 @@ function MathAtan2JS(y, x) {
 
 // ECMA 262 - 15.8.2.6
 function MathCeil(x) {
-  return -MathFloor(-x);
+  return -%_MathFloor(-x);
 }
 
 // ECMA 262 - 15.8.2.8
@@ -67,18 +67,7 @@ function MathExp(x) {
 
 // ECMA 262 - 15.8.2.9
 function MathFloor(x) {
-  x = TO_NUMBER_INLINE(x);
-  // It's more common to call this with a positive number that's out
-  // of range than negative numbers; check the upper bound first.
-  if (x < 0x80000000 && x > 0) {
-    // Numbers in the range [0, 2^31) can be floored by converting
-    // them to an unsigned 32-bit value using the shift operator.
-    // We avoid doing so for -0, because the result of Math.floor(-0)
-    // has to be -0, which wouldn't be the case with the shift.
-    return TO_UINT32(x);
-  } else {
-    return %MathFloorRT(x);
-  }
+  return %_MathFloor(+x);
 }
 
 // ECMA 262 - 15.8.2.10