QmlJS: Fix member completion at the end of a nested object definition.

The parser's error recovery generates three nested object definitions
for code like
Item { Item { font } }
where the innermost definition corresponds to 'font }' and has an empty
lbrace token.

If we create a Range for this recovered definition, code completion will
fail for 'font.'.

Task-number: QTCREATORBUG-2767
Reviewed-by: Roberto Raggi

src/plugins/qmljseditor/qmljseditor.cpp

@@ -404,14 +404,14 @@ protected:
 
     virtual bool visit(AST::UiObjectBinding *ast)
     {
-        if (ast->initializer)
+        if (ast->initializer && ast->initializer->lbraceToken.length)
             _ranges.append(createRange(ast, ast->initializer));
         return true;
     }
 
     virtual bool visit(AST::UiObjectDefinition *ast)
     {
-        if (ast->initializer)
+        if (ast->initializer && ast->initializer->lbraceToken.length)
             _ranges.append(createRange(ast, ast->initializer));
         return true;
     }