Use Prism::Node#tunnel to optimize search in Prism.node_for

Author: eregon

lib/prism/parse_result.rb

@@ -935,8 +935,9 @@ def self.node_for(callable)
     root = parse_result.value
     start_offset = parse_result.source.line_and_character_column_to_byte_offset(start_line, start_column)
     end_offset = parse_result.source.line_and_character_column_to_byte_offset(end_line, end_column)
+    start_byte_column = start_offset - parse_result.source.line_start(start_offset)
 
-    found = root.breadth_first_search do |node|
+    found = root.tunnel(start_line, start_byte_column).reverse.find do |node|
       case node
       when DefNode
         node.start_offset == start_offset && node.end_offset == end_offset