JS implementation of isFinite.

Review URL: http://codereview.chromium.org/1608003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4344 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/runtime.cc

@@ -7100,21 +7100,6 @@ static Object* Runtime_DateDaylightSavingsOffset(Arguments args) {
 }
 
 
-static Object* Runtime_NumberIsFinite(Arguments args) {
-  NoHandleAllocation ha;
-  ASSERT(args.length() == 1);
-
-  CONVERT_DOUBLE_CHECKED(value, args[0]);
-  Object* result;
-  if (isnan(value) || (fpclassify(value) == FP_INFINITE)) {
-    result = Heap::false_value();
-  } else {
-    result = Heap::true_value();
-  }
-  return result;
-}
-
-
 static Object* Runtime_GlobalReceiver(Arguments args) {
   ASSERT(args.length() == 1);
   Object* global = args[0];

src/runtime.h

@@ -210,7 +210,6 @@ namespace internal {
   F(DateYMDFromTime, 2, 1) \
   \
   /* Numbers */ \
-  F(NumberIsFinite, 1, 1) \
   \
   /* Globals */ \
   F(CompileString, 2, 1) \

src/v8natives.js

@@ -82,7 +82,10 @@ function GlobalIsNaN(number) {
 
 // ECMA 262 - 15.1.5
 function GlobalIsFinite(number) {
-  return %NumberIsFinite(ToNumber(number));
+  if (!IS_NUMBER(number)) number = ToNumber(number);
+
+  // NaN - NaN == NaN, Infinity - Infinity == NaN, -Infinity - -Infinity == NaN.
+  return %_IsSmi(number) || number - number == 0;
 }