Add grey to the list of Sass Script colors.

Addresses #738

doc-src/SASS_CHANGELOG.md

@@ -53,6 +53,9 @@ Thanks to Alexander Pavlov for implementing this.
   allows them the same power as Sass-based functions with respect to
   reading and setting variables defined elsewhere in the stylesheet.
 
+* Add "grey" as a recognized SassScript color. Thanks to [Rob
+  Wierzbowski](https://github.com/robwierzbowski).
+
 ### Backwards Incompatibilities -- Must Read!
 
 * Sass will now throw an error when `@extend` is used to extend a selector
@@ -78,6 +81,9 @@ Thanks to Alexander Pavlov for implementing this.
 
 * `Sass::Script::Number::PRECISION` has been removed.
 
+* `grey` is no longer interpreted as a string; it's now interpreted as a color,
+  as per the CSS spec.
+
 ## 3.2.9
 
 * Fix a bug where `@extend`s would occasionally cause a selector to be generated

lib/sass/script/color.rb

@@ -72,6 +72,7 @@ class << self; include Sass::Util; end
         'gold' => 0xffd700,
         'goldenrod' => 0xdaa520,
         'gray' => 0x808080,
+        'grey' => 0x808080,
         'green' => 0x008000,
         'greenyellow' => 0xadff2f,
         'honeydew' => 0xf0fff0,
@@ -171,7 +172,7 @@ class << self; include Sass::Util; end
 
     # Constructs an RGB or HSL color object,
     # optionally with an alpha channel.
-    # 
+    #
     # The RGB values must be between 0 and 255.
     # The saturation and lightness values must be between 0 and 100.
     # The alpha value must be between 0 and 1.
@@ -526,7 +527,7 @@ def hex_str
     def piecewise(other, operation)
       other_num = other.is_a? Number
       if other_num && !other.unitless?
-        raise Sass::SyntaxError.new("Cannot add a number with units (#{other}) to a color (#{self}).") 
+        raise Sass::SyntaxError.new("Cannot add a number with units (#{other}) to a color (#{self}).")
       end
 
       result = []

test/sass/functions_test.rb

@@ -815,8 +815,8 @@ def test_mix_tests_bounds
 
   def test_grayscale
     assert_equal("#bbbbbb", evaluate("grayscale(#abc)"))
-    assert_equal("gray", evaluate("grayscale(#f00)"))
-    assert_equal("gray", evaluate("grayscale(#00f)"))
+    assert_equal("grey", evaluate("grayscale(#f00)"))
+    assert_equal("grey", evaluate("grayscale(#00f)"))
     assert_equal("white", evaluate("grayscale(white)"))
     assert_equal("black", evaluate("grayscale(black)"))
     assert_equal("black", evaluate("grayscale($color: black)"))