[css-sizing] Per WG resolution, make intrinsic sizes definite when they don't depend on 'real' layout.

Author: tabatkins

css-sizing-3/Overview.bs

@@ -83,10 +83,12 @@ Terminology</h2>
 		<dd>
 			A size that can be determined without measuring content;
 			that is, a <<length>>,
+			a measure of text (without consideration of line-wrapping),
 			a size of the <a>initial containing block</a>,
 			or a <<percentage>> or other formula
 			(such the <a href="https://www.w3.org/TR/CSS21/visudet.html#blockwidth">“fill-available” sizing of non-replaced blocks</a> [[CSS21]])
 			that is resolved solely against <a>definite</a> sizes.
+
 			Additionally, the size of the <a>containing block</a> of an absolutely positioned element is always <a>definite</a>
 			with respect to that element.
 

css-sizing/Overview.bs

@@ -82,12 +82,14 @@ Terminology</h2>
 
 		<dt><dfn id="definite" lt="definite|definite size">definite size</dfn>
 		<dd>
-			A size that can be determined without measuring content;
+			A size that can be determined without performing layout;
 			that is, a <<length>>,
+			a measure of text (without consideration of line-wrapping),
 			a size of the <a>initial containing block</a>,
 			or a <<percentage>> or other formula
 			(such the <a href="https://www.w3.org/TR/CSS21/visudet.html#blockwidth">“fill-available” sizing of non-replaced blocks</a> [[CSS21]])
 			that is resolved solely against <a>definite</a> sizes.
+
 			Additionally, the size of the <a>containing block</a> of an absolutely positioned element is always <a>definite</a>
 			with respect to that element.