Lazily initialize fast_sqrt() and pass an Isolate parameter to it

src/x87/codegen-x87.cc

Index: src/x87/codegen-x87.cc
diff --git a/src/x87/codegen-x87.cc b/src/x87/codegen-x87.cc
index 496cfb410a11334db9fea6931649dec49a99004c..87b76508a1098f2b9867c960954e56be78b1d555 100644
--- a/src/x87/codegen-x87.cc
+++ b/src/x87/codegen-x87.cc
@@ -32,21 +32,20 @@ void StubRuntimeCallHelper::AfterCall(MacroAssembler* masm) const {
 
 
 #define __ masm.
-double x87_std_exp(double x, Isolate* isolate) { return std::exp(x); }
 
 UnaryMathFunctionWithIsolate CreateExpFunction(Isolate* isolate) {
-  return x87_std_exp;
+  return nullptr;
 }
 
 
-UnaryMathFunction CreateSqrtFunction() {
+UnaryMathFunctionWithIsolate CreateSqrtFunction(Isolate* isolate) {
   size_t actual_size;
   // Allocate buffer in executable space.
   byte* buffer =
       static_cast<byte*>(base::OS::Allocate(1 * KB, &actual_size, true));
-  if (buffer == NULL) return &std::sqrt;
+  if (buffer == nullptr) return nullptr;
 
-  MacroAssembler masm(NULL, buffer, static_cast<int>(actual_size),
+  MacroAssembler masm(isolate, buffer, static_cast<int>(actual_size),
                       CodeObjectRequired::kNo);
   // Load double input into registers.
   __ fld_d(MemOperand(esp, 4));
@@ -59,9 +58,9 @@ UnaryMathFunction CreateSqrtFunction() {
   masm.GetCode(&desc);
   DCHECK(!RelocInfo::RequiresRelocation(desc));
 
-  Assembler::FlushICacheWithoutIsolate(buffer, actual_size);
+  Assembler::FlushICache(isolate, buffer, actual_size);
   base::OS::ProtectCode(buffer, actual_size);
-  return FUNCTION_CAST<UnaryMathFunction>(buffer);
+  return FUNCTION_CAST<UnaryMathFunctionWithIsolate>(buffer);
 }