Make sure essences have their contents on initialization

If we do not pass the content when building an essence,
`after_initialize` hooks do not have access to the content definitions.

app/models/alchemy/content/factory.rb

@@ -117,7 +117,7 @@ def definition
     #
     def build_essence(attributes = {})
       self.essence = essence_class(essence_type).new(
-        { ingredient: default_value }.merge(attributes)
+        { content: self, ingredient: default_value }.merge(attributes)
       )
     end
 

spec/models/alchemy/essence_headline_spec.rb

@@ -66,4 +66,25 @@
       end
     end
   end
+
+  describe "creating from a content" do
+    it "should have the size and level fields filled with correct defaults" do
+      element = create(:alchemy_element)
+
+      allow(element).to receive(:content_definition_for) do
+        {
+          "name" => "headline",
+          "type" => "EssenceHeadline",
+          "settings" => {
+            "sizes" => [3],
+            "levels" => [2, 3],
+          },
+        }.with_indifferent_access
+      end
+
+      content = Alchemy::Content.create(element: element, name: "headline")
+      expect(content.essence.size).to eq(3)
+      expect(content.essence.level).to eq(2)
+    end
+  end
 end