Custom elements as table rows break layout when importing resources as first business

**I'm submitting a bug report**

* **Library Version:**
1.10.1 and later (have not tested before)

**Please tell us about your environment:**
* **Operating System:**
Windows 10

* **JSPM OR Webpack AND Version**
webpack-cli 3.1.2

* **Browser:**
Tested in Chrome

* **Language:**
all

**Current behavior:**
When using `````` inside a table, where the custom element starts by requiring other resources, the actual rendering is broken.

Given
```
...app.html

...custom-row.html

Start with the app.html and custom-row.html example, or run the linked gist, using the reported webpack-cli environment. Trace how the top-level require in custom-row.html is handled when the component is used as a table row. Done means the rendered table contains a tr with its td child, matching the expected output.

Written by the indexing model from the issue text.