[FromHtml] Handle style nodes wrapping block nodes

[dugancathal]

This fails, currently

  it 'styles blocks wrapped in style nodes' do
    raw_draftjs = FromHtml.new.convert(<<~HTML)
      <div>
        <b>
          <p>Line 1</p>
          <p dir="ltr">Line 2</p>
        </b>
      </div>
    HTML

    expect(raw_draftjs).to eq_raw_draftjs {
      typed_block 'unstyled', 'Line 1'
      inline_style 'BOLD', 0..5
      typed_block 'unstyled', 'Line 2'
      inline_style 'BOLD', 0..5
    }
  end