Enable block variable in view

[toshimaru]

Summary

Enabling block variable in view.

This fixes #27302

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[matthewd]

Instead of excluding the one value here, let's split DELEGATION_RESERVED_METHOD_NAMES in half, between the real keywords (most of them), and the couple (including block) that are just reserved in delegate because they're used in the implementation.

[toshimaru]

I extracted only delegation reserved keywords like this:

$ ruby -v
ruby 2.3.3p222 (2016-11-21 revision 56859) [x86_64-darwin15]

$ cat extract_keywords.rb
original_keywords = %w(_ arg args alias and BEGIN begin block break case class def defined? do else elsif END end ensure false for if in module next nil not or redo rescue retry return self super then true undef unless until when while yield)
keywords = []

original_keywords.each do |keyword|
  begin
    eval("#{keyword} = 1")
  rescue SyntaxError => e
    keywords << keyword
  end
end

p keywords
p original_keywords - keywords

$ ruby extract_keywords.rb
["alias", "and", "BEGIN", "begin", "break", "case", "class", "def", "defined?", "do", "else", "elsif", "END", "end", "ensure", "false", "for", "if", "in", "module", "next", "nil", "not", "or", "redo", "rescue", "retry", "return", "self", "super", "then", "true", "undef", "unless", "until", "when", "while", "yield"]
["_", "arg", "args", "block"]

[toshimaru]

Not sure the constant naming and defined location are good.

@matthewd What do you think?

[matthewd]

96f0df1