Combined with a bullish forecast for the third quarter, upbeat comments from company executives on Amazon’s Prime delivery service and rapid growth in its cloud computing service, Amazon delivered the kind of results Wall Street is looking for. Seattle-based Amazon, which last reported a profit in the 2014 fourth quarter, has often faced worries by investors that its heavy spending on new ventures will not actually pay off. Amazon’s shares had languished for much of last year as the company failed to deliver sustainable profits.