fix(queryAllBySelectText): search using reactive properties (testing-library#124)

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<!-- What changes are being made? (What feature/bug is being fixed here?) -->

**What**:

Replace the existing select query mechanism which uses `HTMLSelectElement .selectedOptions` with a query that searches for the `selected` attribute of an `HTMLOptionElement`.

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**Why**:

Closes testing-library#115.

Since `selectedOptions` is not a reactive property, JSDOM was not updating to match the selected option in a select Element. The `selected` attribute is reactive.

<!-- How were these changes implemented? -->

**How**:

Instead of iterating through `selectedOptions` of an HTMLSelectElement, we iterate through all HTMLSelectOptions and isolate the ones that are selected.
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I've gone ahead and tested this locally to make sure that it would be reactive! 👍 

**Checklist**:

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- [ ] Documentation N/A
- [ ] Tests N/A
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Author: matchai

src/queries.js

@@ -134,11 +134,14 @@ function queryAllBySelectText(
 ) {
   const matcher = exact ? matches : fuzzyMatches
   const matchOpts = {collapseWhitespace, trim}
-  return Array.from(container.querySelectorAll('select')).filter(selectNode =>
-    Array.from(selectNode.selectedOptions).some(optionNode =>
+  return Array.from(container.querySelectorAll('select')).filter(selectNode => {
+    const selectedOptions = Array.from(selectNode.options).filter(
+      option => option.selected,
+    )
+    return selectedOptions.some(optionNode =>
       matcher(getNodeText(optionNode), optionNode, text, matchOpts),
-    ),
-  )
+    )
+  })
 }
 
 function queryBySelectText(...args) {