Pops two strings, compute the equality and put the Boolean result back on the stack.
IMPORTANT
The true meaning of this operator was to apply the String cast to both values, then compare the result as strings. This is not really good JavaScript as per ECMA, so later Macromedia added the strict comparison operators instead. This is why this action should only be used in a Version 4 of SWF. Newer versions should use Strict Equal or plain Equal.