PPC: [Interpreter] Add support for parameter variables.

src/ppc/builtins-ppc.cc

Index: src/ppc/builtins-ppc.cc
diff --git a/src/ppc/builtins-ppc.cc b/src/ppc/builtins-ppc.cc
index bf65eaa69a90d4d97c0754c3c7895eb762ee35b9..96c497697bec06f10582d1677ac966c5d2dc10af 100644
--- a/src/ppc/builtins-ppc.cc
+++ b/src/ppc/builtins-ppc.cc
@@ -991,8 +991,11 @@ void Builtins::Generate_InterpreterExitTrampoline(MacroAssembler* masm) {
 
   // Leave the frame (also dropping the register file).
   __ LeaveFrame(StackFrame::JAVA_SCRIPT);
-  // Drop receiver + arguments.
-  __ Drop(1);  // TODO(rmcilroy): Get number of arguments from BytecodeArray.
+
+  // Drop receiver + arguments and return.
+  __ lwz(r0, FieldMemOperand(kInterpreterBytecodeArrayRegister,
+                             BytecodeArray::kParameterSizeOffset));
+  __ add(sp, sp, r0);
   __ blr();
 }