fix: < > <= >= on aliases to comparable types return boolean

Fixes #844.

Author: hishamhm

spec/lang/operator/lt_spec.lua

@@ -30,4 +30,12 @@ describe("<", function()
    ]], {
       { msg = "cannot use operator '<' for types boolean and integer" }
    }))
+
+   it("< on aliases to comparable types return boolean", util.check([[
+      local type Test = integer
+
+      local function f(a: Test, b: Test) : boolean
+         return a < b
+      end
+   ]]))
 end)

tl.lua

@@ -12623,7 +12623,7 @@ self:expand_type(node, values, elements) })
                   end
                end
 
-               if ua.typename == "nominal" and ub.typename == "nominal" and not meta_on_operator then
+               if (not t) and ua.typename == "nominal" and ub.typename == "nominal" and not meta_on_operator then
                   if self:is_a(ua, ub) then
                      t = ua
                   else

tl.tl

@@ -12623,7 +12623,7 @@ do
                   end
                end
 
-               if ua is NominalType and ub is NominalType and not meta_on_operator then
+               if (not t) and ua is NominalType and ub is NominalType and not meta_on_operator then
                   if self:is_a(ua, ub) then
                      t = ua
                   else