glsl: Update expression types after rebalancing the tree.

glsl: Update expression types after rebalancing the tree.

If we saw a tree that looked like

            vec3
           /   \
         vec3 float
        /   \
      vec3 float
     /   \
   vec3 float

We would see that all of the expression types were vec3, and then
rebalance to

           vec3
        /        \
      vec3       vec3 <-- should be float
     /   \      /    \
   vec3 float float float

This patch adds code to visit the rebalanced tree and update the
expression types from the bottom up.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=80880
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>