Fixed a crash in MS Office 2010 Chinese version.
Thanks Jiang Yike for the helps on testing :)

---
 dlls/imm32/imm.c         |    6 ++++++
 dlls/imm32/tests/imm32.c |   13 +++++++++++++
 2 files changed, 19 insertions(+)

+    if (IsBadReadPtr(internal, sizeof(HIMCC)))
+    {
+        SetLastError(ERROR_INVALID_HANDLE);
+        return 0;
+    }
+

Do you really need this for Office 2010 or null check is enough? If it's passing 0 handle here
that's what you should check imho. If HIMCC is really a handle and not a struct pointer like in wine,
that's not how a handle validity check will look like.