As of Unicode 6.3, Mongolian Vowel Separator is not whitespace

Ruby 2.2 knows this, and no longer matches it with [[:space:]], so it's
not a good candidate for testing String#squish.

activesupport/lib/active_support/core_ext/string/filters.rb

@@ -3,7 +3,7 @@ class String
   # the string, and then changing remaining consecutive whitespace
   # groups into one space each.
   #
-  # Note that it handles both ASCII and Unicode whitespace like mongolian vowel separator (U+180E).
+  # Note that it handles both ASCII and Unicode whitespace.
   #
   #   %{ Multi-line
   #      string }.squish                   # => "Multi-line string"

activesupport/lib/active_support/multibyte/unicode.rb

@@ -42,7 +42,6 @@ module ActiveSupport
         0x0085,                # White_Space # Cc       <control-0085>
         0x00A0,                # White_Space # Zs       NO-BREAK SPACE
         0x1680,                # White_Space # Zs       OGHAM SPACE MARK
-        0x180E,                # White_Space # Zs       MONGOLIAN VOWEL SEPARATOR
         (0x2000..0x200A).to_a, # White_Space # Zs  [11] EN QUAD..HAIR SPACE
         0x2028,                # White_Space # Zl       LINE SEPARATOR
         0x2029,                # White_Space # Zp       PARAGRAPH SEPARATOR

activesupport/test/core_ext/string_ext_test.rb

@@ -189,10 +189,10 @@ class StringInflectionsTest < ActiveSupport::TestCase
   end
 
   def test_string_squish
-    original = %{\u180E\u180E A string surrounded by unicode mongolian vowel separators,
-      with tabs(\t\t), newlines(\n\n), unicode nextlines(\u0085\u0085) and many spaces(  ). \u180E\u180E}
+    original = %{\u205f\u3000 A string surrounded by various unicode spaces,
+      with tabs(\t\t), newlines(\n\n), unicode nextlines(\u0085\u0085) and many spaces(  ). \u00a0\u2007}
 
-    expected = "A string surrounded by unicode mongolian vowel separators, " +
+    expected = "A string surrounded by various unicode spaces, " +
       "with tabs( ), newlines( ), unicode nextlines( ) and many spaces( )."
 
     # Make sure squish returns what we expect:

guides/source/active_support_core_extensions.md

@@ -1268,7 +1268,7 @@ The method `squish` strips leading and trailing whitespace, and substitutes runs
 
 There's also the destructive version `String#squish!`.
 
-Note that it handles both ASCII and Unicode whitespace like mongolian vowel separator (U+180E).
+Note that it handles both ASCII and Unicode whitespace.
 
 NOTE: Defined in `active_support/core_ext/string/filters.rb`.