unresolved external symbol in nsAString::BeginReading() in xul-runner 10.0.2

I'm using the xul-runner 10.0.2 and the Embedded-API. Inside of the
Embedded-API there is the following code:
...
nsresult MozView::LoadURI(const char *aUri)
{
    return mPrivate->mWebNavigation-
>LoadURI(NS_ConvertUTF8toUTF16(aUri).get(),
 
nsIWebNavigation::LOAD_FLAGS_NONE,
                                             0, 0, 0);
}
...
This code works fine with xul-runner 2. But if I try to build this
code with xul-runner 10.0.2 I get the following linker error:
...
Error	24	error LNK2019: unresolved external symbol "public: unsigned
short const * __thiscall nsAString::BeginReading(void)const " (?
BeginReading@nsAString@@QBEPBGXZ) referenced in function "public:
unsigned short const * __thiscall nsString_external::get(void)const
" (?get@nsString_external@@QBEPBGXZ)	embed.obj	HTMLRenderer
...

I tried to adapt the option 'Treat wchar_t as Built-in Type' with
"yes" and "no" in my project settings as described here:
https://developer.mozilla.org/En/Developer_Guide/Build_Instructions#Build_and_install

But without success; always the same linker error. I'm using VS2008
with C++. Did someone have similar problems?