In Interface_field_reference_expression, the interface expression
    is used in two places, so a temporary variable is used. Previously,
    we used a Set_and_use_temporary_expression, which, when evaluated
    twice, causes double evaluation of the underlying expression. Fix
    by setting the temporary once and use Temporary_reference_expression
    instead.
    
    Fixes golang/go#26248.
    
    Reviewed-on: https://go-review.googlesource.com/122756

From-SVN: r262533