It should be parsed as an DeclarationStatement, but instead it was
parsed as an ExpressionStatement.

Regression introduced with

    commit d3c5fff6

.
    C++: Fix expensive parsing of expressions

The introduced ASTCache did not save the correct return value of a
parse* function. Because of that, the first return in
Parser::parseExpressionList returned false on the second invocation
(cache hit), instead of true, which resulted in an ExpressionStatement.

Task-number: QTCREATORBUG-13122
Change-Id: I8dbd8852b0909edddcd3195b484f4cea92328cc5
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>