Fix a false positive for Layout/ClosingParenthesisIndentation

This PR fixes a false negative for `Layout/ClosingParenthesisIndentation` when first argument is multiline.

The following is a reproduction step.
```bash
% rubocop -V
0.59.2 (using Parser 2.5.1.2, running on ruby 2.5.0 x86_64-darwin17)

% cat app/models/users.rb
class User < ApplicationRecord
  def self.complex_find
    where(
      "users.approved_at < ? OR
       users.approved_at IS NULL", 3.days.ago
    )
  end
end

% rubocop app/models/users.rb --only Layout/ClosingParenthesisIndentation -d
or /Users/anton/code/rubocop: configuration from /Users/anton/code/rubocop/.rubocop.yml
configuration from /Users/anton/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/rubocop-rspec-1.29.1/config/default.yml
configuration from /Users/anton/.rbenv/versions/2.5.0/lib/ruby/gems/2.5.0/gems/rubocop-rspec-1.29.1/config/default.yml
Default configuration from /Users/anton/code/rubocop/config/default.yml
Inheriting configuration from /Users/anton/code/rubocop/.rubocop_todo.yml
Inspecting 1 file
Scanning /Users/anton/code/rubocop/users.rb
C

Offenses:

users.rb:6:5: C: Layout/ClosingParenthesisIndentation: Indent ) to column 5 (not 4)
    )
    ^

1 file inspected, 1 offense detected
Finished in 0.5669199999974808 seconds
```

CHANGELOG.md

@@ -11,6 +11,7 @@
 * [#6389](https://github.com/rubocop-hq/rubocop/pull/6389): Fix false negative for `Style/TrailingCommaInHashLitera`/`Style/TrailingCommaInArrayLiteral` when there is a comment in the last line. ([@bayandin][])
 * [#6566](https://github.com/rubocop-hq/rubocop/issues/6566): Fix false positive for `Layout/EmptyLinesAroundAccessModifier` when at the end of specifying a superclass is missing blank line. ([@koic][])
 * [#6571](https://github.com/rubocop-hq/rubocop/issues/6571): Fix a false positive for `Layout/TrailingCommaInArguments` when a line break before a method call and `EnforcedStyleForMultiline` is set to `consistent_comma`. ([@koic][])
+* [#6351](https://github.com/rubocop-hq/rubocop/pull/6351): Fix a false positive for `Layout/ClosingParenthesisIndentation` when first argument is multiline. ([@antonzaytsev][])
 
 ## 0.61.1 (2018-12-06)
 
@@ -3696,3 +3697,4 @@
 [@tom-lord]: https://github.com/tom-lord
 [@bayandin]: https://github.com/bayandin
 [@nadiyaka]: https://github.com/nadiyaka
+[@antonzaytsev]: https://github.com/antonzaytsev

lib/rubocop/cop/layout/closing_parenthesis_indentation.rb

@@ -146,7 +146,7 @@ def expected_column(left_paren, elements)
             left_paren.column
           else
             source_indent = processed_source
-                            .line_indentation(last_argument_line(elements))
+                            .line_indentation(first_argument_line(elements))
             new_indent    = source_indent - indentation_width
 
             new_indent < 0 ? 0 : new_indent
@@ -160,9 +160,9 @@ def all_elements_aligned?(elements)
             .count == 1
         end
 
-        def last_argument_line(elements)
+        def first_argument_line(elements)
           elements
-            .last
+            .first
             .loc
             .first_line
         end

spec/rubocop/cop/layout/closing_parenthesis_indentation_spec.rb

@@ -495,6 +495,27 @@ def some_method()
     end
   end
 
+  context 'method call with first multiline arg on new line' do
+    it 'accepts ) on the same level as ( with args on same line' do
+      expect_no_offenses(<<-RUBY.strip_indent)
+        where(
+          "multiline
+           condition", second_arg
+        )
+      RUBY
+    end
+
+    it 'accepts ) on the same level as ( with second arg on new line' do
+      expect_no_offenses(<<-RUBY.strip_indent)
+        where(
+          "multiline
+           condition",
+          second_arg
+        )
+      RUBY
+    end
+  end
+
   it 'accepts begin nodes that are not grouped expressions' do
     expect_no_offenses(<<-RUBY.strip_indent)
       def a