[Interpreter] Add support for parameter variables.

src/mips64/builtins-mips64.cc

Index: src/mips64/builtins-mips64.cc
diff --git a/src/mips64/builtins-mips64.cc b/src/mips64/builtins-mips64.cc
index 843daa1ee5cfb495a0c0bb9c280e022e714ff6af..c576183a2627bf5ec1745a1b51d5d9f33d44c033 100644
--- a/src/mips64/builtins-mips64.cc
+++ b/src/mips64/builtins-mips64.cc
@@ -993,8 +993,11 @@ 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.
+  __ lw(at, FieldMemOperand(kInterpreterBytecodeArrayRegister,
+                            BytecodeArray::kParameterSizeOffset));
+  __ Daddu(sp, sp, at);
   __ Jump(ra);
 }