PPC: [Interpreter] Add support for parameter variables.

Port 5d975694

Original commit message:
    Adds support for parameters to the BytecodeArrayBuilder and BytecodeGenerator.
    Parameters are accessed as negative interpreter registers.

R=rmcilroy@chromium.org, jyan@ca.ibm.com, dstence@us.ibm.com, joransiu@ca.ibm.com
BUG=v8:4280
LOG=N

Review URL: https://codereview.chromium.org/1308373003

Cr-Commit-Position: refs/heads/master@{#30424}

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();
 }