Remove Mutant.constant_lookup

* Since ruby-2.1 Object.const_get does nested lookups fine

lib/mutant.rb

@@ -41,20 +41,6 @@ module Mutant
     ENV.key?('CI')
   end
 
-  # Lookup constant for location
-  #
-  # @param [String] location
-  #
-  # @return [Object]
-  #
-  # @api private
-  #
-  def self.constant_lookup(location)
-    location.split(SCOPE_OPERATOR).reduce(Object) do |parent, name|
-      parent.const_get(name, nil)
-    end
-  end
-
   # Perform self zombification
   #
   # @return [self]

lib/mutant/expression/method.rb

@@ -48,7 +48,7 @@ module Mutant
       # @api private
       #
       def scope
-        Mutant.constant_lookup(scope_name)
+        Object.const_get(scope_name)
       end
 
       # Return method name

lib/mutant/expression/methods.rb

@@ -60,7 +60,7 @@ module Mutant
       # @api private
       #
       def scope
-        Mutant.constant_lookup(scope_name)
+        Object.const_get(scope_name)
       end
 
       # Return scope symbol

lib/mutant/expression/namespace.rb

@@ -81,7 +81,7 @@ module Mutant
         # @api private
         #
         def matcher(env)
-          Matcher::Scope.new(env, Mutant.constant_lookup(namespace), self)
+          Matcher::Scope.new(env, Object.const_get(namespace), self)
         end
 
       end # Exact