Type inference on type application

[soutaro]

Possible issue found at: https://github.com/ruby/lrama/pull/19/files#diff-ab21254dba99ec48bfb2ce485b2f9b988a3ddc3d4c651d1aed8bd2ec5334e0ecR278.

# @type var s: Array[[Integer, Integer]]
s = actions.each_with_index.map do |n, i|
  [i, n] #: [Integer, Integer]
end

Why we have both variable type declaration and block type assertion.

# This should work
s = actions.each_with_index.map do |n, i|
  [i, n] #: [Integer, Integer]
end

# Or this
# @type var s: Array[[Integer, Integer]]
s = actions.each_with_index.map do |n, i|
  [i, n]
end