diff -r 000000000000 -r 6474c204b198 xpcom/reflect/xptcall/src/md/win32/xptcinvoke.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/reflect/xptcall/src/md/win32/xptcinvoke.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,74 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Platform specific code to invoke XPCOM methods on native objects */
+
+#include "xptcprivate.h"
+
+#ifndef WIN32
+#error "This code is for Win32 only"
+#endif
+
+static void __fastcall
+invoke_copy_to_stack(uint32_t* d, uint32_t paramCount, nsXPTCVariant* s)
+{
+    for(; paramCount > 0; paramCount--, d++, s++)
+    {
+        if(s->IsPtrData())
+        {
+            *((void**)d) = s->ptr;
+            continue;
+        }
+        switch(s->type)
+        {
+        case nsXPTType::T_I8     : *((int8_t*)  d) = s->val.i8;          break;
+        case nsXPTType::T_I16    : *((int16_t*) d) = s->val.i16;         break;
+        case nsXPTType::T_I32    : *((int32_t*) d) = s->val.i32;         break;
+        case nsXPTType::T_I64    : *((int64_t*) d) = s->val.i64; d++;    break;
+        case nsXPTType::T_U8     : *((uint8_t*) d) = s->val.u8;          break;
+        case nsXPTType::T_U16    : *((uint16_t*)d) = s->val.u16;         break;
+        case nsXPTType::T_U32    : *((uint32_t*)d) = s->val.u32;         break;
+        case nsXPTType::T_U64    : *((uint64_t*)d) = s->val.u64; d++;    break;
+        case nsXPTType::T_FLOAT  : *((float*)   d) = s->val.f;           break;
+        case nsXPTType::T_DOUBLE : *((double*)  d) = s->val.d;   d++;    break;
+        case nsXPTType::T_BOOL   : *((bool*)  d) = s->val.b;           break;
+        case nsXPTType::T_CHAR   : *((char*)    d) = s->val.c;           break;
+        case nsXPTType::T_WCHAR  : *((wchar_t*) d) = s->val.wc;          break;
+        default:
+            // all the others are plain pointer types
+            *((void**)d) = s->val.p;
+            break;
+        }
+    }
+}
+
+#pragma warning(disable : 4035) // OK to have no return value
+// Tell the PDB file this function has a standard frame pointer, and not to use
+// a custom FPO program.
+#pragma optimize( "y", off )
+extern "C" NS_EXPORT nsresult NS_FROZENCALL
+NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
+                 uint32_t paramCount, nsXPTCVariant* params)
+{
+    __asm {
+        mov     edx,paramCount      // Save paramCount for later
+        test    edx,edx             // maybe we don't have any params to copy
+        jz      noparams
+        mov     eax,edx             
+        shl     eax,3               // *= 8 (max possible param size)
+        sub     esp,eax             // make space for params
+        mov     ecx,esp
+        push    params
+        call    invoke_copy_to_stack // fastcall, ecx = d, edx = paramCount, params is on the stack
+noparams:
+        mov     ecx,that            // instance in ecx
+        push    ecx                 // push this
+        mov     edx,[ecx]           // vtable in edx
+        mov     eax,methodIndex
+        call    [edx][eax*4]        // stdcall, i.e. callee cleans up stack.
+        mov     esp,ebp
+    }
+}
+#pragma warning(default : 4035) // restore default