Introduce fewer intermediate variables

[Fleli]

When declaring new variables with an initial RHS, an intermediate variable for the RHS is first calculated and then assigned to the newly declared variable.

This is done so that the outer x is used on the RHS, instead of a newly declared x, in declarations like var x = x + 5;.

Suggestion: Only do it this way if the LHS variable (name) is used on the RHS. Otherwise, first declare and then assign (which eliminates the intermediate variable).