Embedding node into block under constant

* Creates exactly the same ast as the ruby parser would do.

lib/mutant/context/constant.rb

@@ -35,7 +35,8 @@ module Mutant
       #
       def root(node)
         root = root_ast
-        root.body = @scope_class.new(1, root.name, node)
+        block = Rubinius::AST::Block.new(1, [node])
+        root.body = @scope_class.new(1, root.name, block)
         Rubinius::AST::Script.new(root)
       end
 

spec/unit/mutant/context/constant/root_spec.rb

@@ -16,7 +16,9 @@ describe Mutant::Context::Constant, '#root' do
     scope.should be_kind_of(Rubinius::AST::ModuleScope)
   end
 
-  it 'should place the ast under scope' do
-    scope_body.should be(node)
+  it 'should place the ast under scope inside of block' do
+    scope_body.should be_a(Rubinius::AST::Block)
+    scope_body.array.should eql([node])
+    scope_body.array.first.should be(node)
   end
 end