[Sass] Get rid of some unnecessary error line specifications.

lib/sass/files.rb

@@ -77,7 +77,7 @@ module Sass
 
       return new_filename if new_filename
       return filename + '.css' unless was_sass
-      raise SyntaxError.new("File to import not found or unreadable: #{original_filename}.", @line)
+      raise SyntaxError.new("File to import not found or unreadable: #{original_filename}.")
     end
 
     private

lib/sass/script/parser.rb

@@ -158,7 +158,7 @@ END
         if try_tok(:single_eq)
           val = assert_expr(:concat)
         elsif must_have_default
-          raise SyntaxError.new("Required argument #{var.inspect} must come before any optional arguments.", @line)
+          raise SyntaxError.new("Required argument #{var.inspect} must come before any optional arguments.")
         end
 
         return [[var, val]] unless try_tok(:comma)

lib/sass/tree/mixin_node.rb

@@ -24,7 +24,7 @@ module Sass::Tree
     # @raise [Sass::SyntaxError] if an incorrect number of arguments was passed
     # @see Sass::Tree
     def _perform(environment)
-      raise Sass::SyntaxError.new("Undefined mixin '#{@name}'.", @line) unless mixin = environment.mixin(@name)
+      raise Sass::SyntaxError.new("Undefined mixin '#{@name}'.") unless mixin = environment.mixin(@name)
 
       raise Sass::SyntaxError.new(<<END.gsub("\n", "")) if mixin.args.size < @args.size
 Mixin #{@name} takes #{mixin.args.size} argument#{'s' if mixin.args.size != 1}