Update partitioning to strip empty elements

lib/outlook/internal_tree/raw_internal_basic.ex

@@ -53,6 +53,7 @@ defmodule Outlook.InternalTree.RawInternalBasic do
   defp inline_to_translation_units(inline_tree) do
     partition_inlinelevel(inline_tree)
     |> chunk_with_list()
+    |> Enum.map(fn sentence -> strip_empty_nodes(sentence) end)
     |> Enum.map(fn sentence -> Html.strip_attributes(sentence) end)
     |> Enum.map(fn sentence ->
       %TranslationUnit{
@@ -90,6 +91,25 @@ defmodule Outlook.InternalTree.RawInternalBasic do
   def partition_inlinelevel([]), do: []
 
 
+  def strip_empty_nodes([%{type: :element} = node | rest]) do
+    content = strip_empty_nodes(node.content)
+    case content do
+      [] -> strip_empty_nodes(rest)
+      _  -> [ %InternalNode{node | content: content} | strip_empty_nodes(rest) ]
+    end
+  end
+
+  def strip_empty_nodes([%{type: :text, content: ""} | rest]) do
+    strip_empty_nodes(rest)
+  end
+
+  def strip_empty_nodes([node | rest]) do
+    [ node | strip_empty_nodes(rest) ]
+  end
+
+  def strip_empty_nodes([]), do: []
+
+
   def strip_empty_tunits([ %TranslationUnit{content: ""} | rest]) do
     strip_empty_tunits(rest)
   end