Require text inputs to be scroll containers

And only support scrolling in the inline axis.

This should address the third bullet point in
#4082 (comment)

source

@@ -3721,6 +3721,7 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
  <ul class="brief">
  <li>The <dfn data-x-href="https://drafts.csswg.org/css-overflow/#propdef-overflow">'overflow'</dfn> property and its <dfn data-x-href="https://drafts.csswg.org/css-overflow/#valdef-overflow-hidden">'hidden'</dfn> value</li>
  <li>The <dfn data-x-href="https://drafts.csswg.org/css-overflow/#propdef-text-overflow">'text-overflow'</dfn> property</li>
+ <li>The term <dfn data-x-href="https://drafts.csswg.org/css-overflow/#scroll-container">scroll container</dfn>
  </ul>
 
  <p>The following features are defined in <cite>CSS Positioned Layout</cite>: <ref
@@ -3773,6 +3774,8 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
  <li>The <dfn data-x-href="https://drafts.csswg.org/css-writing-modes/#direction">'direction'</dfn> property</li>
  <li>The <dfn data-x-href="https://drafts.csswg.org/css-writing-modes/#unicode-bidi">'unicode-bidi'</dfn> property</li>
  <li>The <dfn data-x-href="https://drafts.csswg.org/css-writing-modes/#block-flow-direction">block flow direction</dfn>,
+ <dfn data-x-href="https://drafts.csswg.org/css-writing-modes/#block-axis">block axis</dfn>,
+ <dfn data-x-href="https://drafts.csswg.org/css-writing-modes/#inline-axis">inline axis</dfn>,
  <dfn data-x-href="https://drafts.csswg.org/css-writing-modes/#block-size">block size</dfn>,
  <dfn data-x-href="https://drafts.csswg.org/css-writing-modes/#inline-size">inline size</dfn>,
  <dfn data-x-href="https://drafts.csswg.org/css-writing-modes/#block-start">block-start</dfn>,
@@ -115296,6 +115299,10 @@ details[open] > summary {
  in pixels, and <var>max</var> is the maximum character width of that same font, also in
  pixels. (The element's <span>'letter-spacing'</span> property does not affect the result.)</p>
 
+ <p>These text controls are expected to be <span data-x="scroll container">scroll
+ containers</span> and support scrolling in the <span>inline axis</span>, but not the <span>block
+ axis</span>.</p>
+
  </div>