[builtins] Provide Math.floor as TurboFan builtin.

src/compiler/js-intrinsic-lowering.cc

Index: src/compiler/js-intrinsic-lowering.cc
diff --git a/src/compiler/js-intrinsic-lowering.cc b/src/compiler/js-intrinsic-lowering.cc
index ac882f71147df2d7505efc323f1e85d5252143d8..5ca08c411bafda2cb85b608bc92b95b545647ebe 100644
--- a/src/compiler/js-intrinsic-lowering.cc
+++ b/src/compiler/js-intrinsic-lowering.cc
@@ -57,8 +57,6 @@ Reduction JSIntrinsicLowering::Reduce(Node* node) {
       return ReduceIsSmi(node);
     case Runtime::kInlineMathClz32:
       return ReduceMathClz32(node);
-    case Runtime::kInlineMathFloor:
-      return ReduceMathFloor(node);
     case Runtime::kInlineValueOf:
       return ReduceValueOf(node);
     case Runtime::kInlineFixedArrayGet:
@@ -216,12 +214,6 @@ Reduction JSIntrinsicLowering::ReduceMathClz32(Node* node) {
 }
 
 
-Reduction JSIntrinsicLowering::ReduceMathFloor(Node* node) {
-  if (!machine()->Float64RoundDown().IsSupported()) return NoChange();
-  return Change(node, machine()->Float64RoundDown().op());
-}
-
-
 Reduction JSIntrinsicLowering::ReduceValueOf(Node* node) {
   // if (%_IsSmi(value)) {
   //   return value;