mshtml: Properly handle NULL value in set_nsstyle_attr.

dlls/mshtml/htmlstyle.c

@@ -351,16 +351,18 @@ static LPWSTR fix_url_value(LPCWSTR val)
     return ret;
 }
 
-HRESULT set_nsstyle_attr(nsIDOMCSSStyleDeclaration *nsstyle, styleid_t sid, LPCWSTR value, DWORD flags)
+HRESULT set_nsstyle_attr(nsIDOMCSSStyleDeclaration *nsstyle, styleid_t sid, const WCHAR *value, DWORD flags)
 {
     nsAString str_name, str_value, str_empty;
     LPWSTR val = NULL;
     nsresult nsres;
 
+    if(value) {
         if(flags & ATTR_FIX_PX)
             val = fix_px_value(value);
         if(flags & ATTR_FIX_URL)
             val = fix_url_value(value);
+    }
 
     nsAString_InitDepend(&str_name, style_tbl[sid].name);
     nsAString_InitDepend(&str_value, val ? val : value);

dlls/mshtml/tests/style.c

@@ -1052,6 +1052,19 @@ static void test_body_style(IHTMLStyle *style)
     ok(!strcmp_wa(V_BSTR(&v), "70px"), "V_BSTR(v) = %s\n", wine_dbgstr_w(V_BSTR(&v)));
     VariantClear(&v);
 
+    V_VT(&v) = VT_BSTR;
+    V_BSTR(&v) = NULL;
+    hres = IHTMLStyle_put_height(style, v);
+    ok(hres == S_OK, "put_height failed: %08x\n", hres);
+    VariantClear(&v);
+
+    V_VT(&v) = VT_EMPTY;
+    hres = IHTMLStyle_get_height(style, &v);
+    ok(hres == S_OK, "get_height failed: %08x\n", hres);
+    ok(V_VT(&v) == VT_BSTR, "V_VT(v)=%d\n", V_VT(&v));
+    ok(!V_BSTR(&v), "V_BSTR(v) = %s, expected NULL\n", wine_dbgstr_w(V_BSTR(&v)));
+    VariantClear(&v);
+
     V_VT(&v) = VT_I4;
     V_I4(&v) = 64;
     hres = IHTMLStyle_put_height(style, v);