Revert of [builtins] Introduce proper Float64Exp operator.

src/runtime/runtime-maths.cc

 // Copyright 2014 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.
 
 #include "src/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/assembler.h"
 #include "src/base/utils/random-number-generator.h"
 #include "src/bootstrapper.h"
@@ skipping 41 matching lines @@
   DCHECK(args.length() == 2);
   CONVERT_DOUBLE_ARG_CHECKED(x, 0);
   CONVERT_ARG_CHECKED(JSTypedArray, result, 1);
   CHECK(result->byte_length() == Smi::FromInt(2 * sizeof(double)));
   FixedFloat64Array* array = FixedFloat64Array::cast(result->elements());
   double* y = static_cast<double*>(array->DataPtr());
   return Smi::FromInt(fdlibm::rempio2(x, y));
 }
 
 
+RUNTIME_FUNCTION(Runtime_MathExpRT) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 1);
+  isolate->counters()->math_exp_runtime()->Increment();
+
+  CONVERT_DOUBLE_ARG_CHECKED(x, 0);
+  lazily_initialize_fast_exp(isolate);
+  return *isolate->factory()->NewNumber(fast_exp(x, isolate));
+}
+
+
 // Slow version of Math.pow.  We check for fast paths for special cases.
 // Used if VFP3 is not available.
 RUNTIME_FUNCTION(Runtime_MathPow) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 2);
   isolate->counters()->math_pow_runtime()->Increment();
 
   CONVERT_DOUBLE_ARG_CHECKED(x, 0);
 
   // If the second argument is a smi, it is much faster to call the
@@ skipping 79 matching lines @@
     base::RandomNumberGenerator::XorShift128(&state0, &state1);
     array[i] = base::RandomNumberGenerator::ToDouble(state0, state1);
   }
   // Persist current state.
   array[kState0Offset] = uint64_to_double(state0);
   array[kState1Offset] = uint64_to_double(state1);
   return *typed_array;
 }
 }  // namespace internal
 }  // namespace v8