Revert of [builtins] Introduce proper Float64Exp operator.

src/crankshaft/hydrogen.cc

 // Copyright 2013 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/crankshaft/hydrogen.h"
 
 #include <sstream>
 
 #include "src/allocation-site-scopes.h"
 #include "src/ast/ast-numbering.h"
@@ skipping 8838 matching lines @@
 }
 
 
 bool HOptimizedGraphBuilder::TryInlineBuiltinFunctionCall(Call* expr) {
   if (!expr->target()->shared()->HasBuiltinFunctionId()) return false;
   BuiltinFunctionId id = expr->target()->shared()->builtin_function_id();
   // We intentionally ignore expr->tail_call_mode() here because builtins
   // we inline here do not observe if they were tail called or not.
   switch (id) {
     case kMathExp:
+      if (!FLAG_fast_math) break;
+      // Fall through if FLAG_fast_math.
     case kMathRound:
     case kMathFround:
     case kMathFloor:
     case kMathAbs:
     case kMathSqrt:
     case kMathLog:
     case kMathClz32:
       if (expr->arguments()->length() == 1) {
         HValue* argument = Pop();
         Drop(2);  // Receiver and function.
@@ skipping 4831 matching lines @@
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 }  // namespace internal
 }  // namespace v8