Revert "Merge pull request #478 from Shopify/numbers-in-identifiers"

This reverts commit 263e90e772, reversing
changes made to 4dc682313f.

test/unit/lexer_unit_test.rb

@@ -32,10 +32,7 @@ class LexerUnitTest < Minitest::Test
 
   def test_fancy_identifiers
     tokens = Lexer.new('hi five?').tokenize
-    assert_equal [[:id, 'hi'], [:id, 'five?'], [:end_of_string]], tokens
-
-    tokens = Lexer.new('2foo').tokenize
-    assert_equal [[:number, '2'], [:id, 'foo'], [:end_of_string]], tokens
+    assert_equal [[:id,'hi'], [:id, 'five'], [:question, '?'], [:end_of_string]], tokens
   end
 
   def test_whitespace