[es2015] Precompute the descriptive string for symbols.

src/builtins/ia32/builtins-ia32.cc

Index: src/builtins/ia32/builtins-ia32.cc
diff --git a/src/builtins/ia32/builtins-ia32.cc b/src/builtins/ia32/builtins-ia32.cc
index bcffedfef2ba51010fbfff161b626e0b1a82a4a9..b2522f49b90f138eda8686f3a0ab6de45e69dfe0 100644
--- a/src/builtins/ia32/builtins-ia32.cc
+++ b/src/builtins/ia32/builtins-ia32.cc
@@ -2009,13 +2009,8 @@ void Builtins::Generate_StringConstructor(MacroAssembler* masm) {
 
   // 3b. Convert symbol in eax to a string.
   __ bind(&symbol_descriptive_string);
-  {
-    __ PopReturnAddressTo(ecx);
-    __ lea(esp, Operand(esp, ebx, times_pointer_size, kPointerSize));
-    __ Push(eax);
-    __ PushReturnAddressFrom(ecx);
-    __ TailCallRuntime(Runtime::kSymbolDescriptiveString);
-  }
+  __ mov(eax, FieldOperand(eax, Symbol::kDescriptiveStringOffset));
+  // Fall through.
 
   __ bind(&drop_frame_and_ret);
   {