SAS.ts assumes arrays are from the same JS realm

[freaktechnik]

SAS.ts assumes the array from the SAS response is from the same JS realm, since it uses instanceof Array to detect if it really got an array:

matrix-js-sdk/src/crypto/verification/SAS.ts

Line 220 in dddc0ae

return anArray instanceof Array ? anArray.filter(x => aSet.has(x)) : [];

However, with the switch to fetch the arrays in parsed JSON responses don't come from the same JS realm as the SDK is running in (apparently). Changing the code to use Array.isArray fixes the issues for us.