Why do expectations of inflation decrease SRAS (Short Run Aggregate supply)? If firms and workers expect the prices to rise, the short run aggregate supply will shift to the left to SRAS2.
  (https://www.albert.io/blog/what-shifts-aggregate-demand-and-supply-ap-macroeconomics-review/)


In other words, the SRAS will DECREASE. But why? Especially considering that firms react with increased output supplied to inflation in the short run. According to theory of sticky prices such reaction happens because many firms with flexible output prices see increased inflation as chance to rip additional profit in the short run. So why would they decrease quantity supplied at all possible price levels (i.e. shift SRAS to the left) when they expect inflation to increase?
That’s because you are confusing inflation expectation (increases in prices in the future) with just inflation (i.e. increasing prices now). If aggregate prices increase quantity produced would increase. However, an expectation of price increases in future shifts supply curve to the left as businesses will prefer just to hold on the inventory today and sell it in the future at higher price. If you have an apple and you get option of selling it today for 10e or week after for 50e you will probably prefer the latter (ignoring potential behavioral effects such as hyperbolic discounting and assuming rationality). This will shift the supply of apples in the short run to the left.

Similarly when it comes to aggregate demand higher inflation expectations would actually increase demand, because if you expect prices to be high in the future you want to buy stuff you want now. 

You should be very careful not to confuse inflation expectations and inflation they work completely differently.