X87: Partial revert of rest parameter desugaring.

src/x87/code-stubs-x87.cc

Index: src/x87/code-stubs-x87.cc
diff --git a/src/x87/code-stubs-x87.cc b/src/x87/code-stubs-x87.cc
index 70f3e27f641d5966c8af39f474cbadc7f1557926..fc10a9b995866a11dac8cc30eab48fee1357fee6 100644
--- a/src/x87/code-stubs-x87.cc
+++ b/src/x87/code-stubs-x87.cc
@@ -853,6 +853,32 @@ void ArgumentsAccessStub::GenerateNewStrict(MacroAssembler* masm) {
 }
 
 
+void RestParamAccessStub::GenerateNew(MacroAssembler* masm) {
+  // esp[0] : return address
+  // esp[4] : language mode
+  // esp[8] : index of rest parameter
+  // esp[12] : number of parameters
+  // esp[16] : receiver displacement
+
+  // Check if the calling frame is an arguments adaptor frame.
+  Label runtime;
+  __ mov(edx, Operand(ebp, StandardFrameConstants::kCallerFPOffset));
+  __ mov(ecx, Operand(edx, StandardFrameConstants::kContextOffset));
+  __ cmp(ecx, Immediate(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
+  __ j(not_equal, &runtime);
+
+  // Patch the arguments.length and the parameters pointer.
+  __ mov(ecx, Operand(edx, ArgumentsAdaptorFrameConstants::kLengthOffset));
+  __ mov(Operand(esp, 3 * kPointerSize), ecx);
+  __ lea(edx,
+         Operand(edx, ecx, times_2, StandardFrameConstants::kCallerSPOffset));
+  __ mov(Operand(esp, 4 * kPointerSize), edx);
+
+  __ bind(&runtime);
+  __ TailCallRuntime(Runtime::kNewRestParam, 4, 1);
+}
+
+
 void RegExpExecStub::Generate(MacroAssembler* masm) {
   // Just jump directly to runtime if native RegExp is not selected at compile
   // time or if regexp entry in generated code is turned off runtime switch or