[css-tables] Clarified percent heights in table-cells

https://bugs.chromium.org/p/chromium/issues/detail?id=671010
(updated after discussing with Greg)

Author: FremyCompany

css-tables-3/Overview.bs

@@ -857,7 +857,7 @@ spec:css22; type:property; text:display
 					is ignored and treated as if its value was <code>visible</code>.
 
 				<li>All css properties of <a>table-column</a> and <a>table-column-group</a> boxes are ignored,
-					except when explicitely specified by this specification.
+					except when explicitly specified by this specification.
 
 				<li>The 'position' of <a>table-track</a> and <a>table-track-grouping</a> boxes is ignored
 					if its value is <code>relative</code>. User agents that support 'transform'
@@ -1821,10 +1821,11 @@ spec:css22; type:property; text:display
 					where, if appropriate, percentage-based heights are this time resolved 
 					against their parent cell used height.
 				It is appropriate to resolve percentage heights on direct children of table cells
-					if the cell is considered to have a height specified by the author.
-				In addition to the cases already described in <a href="http://www.w3.org/TR/CSS2/visudet.html#the-height-property">CSS 2</a>,
-					it is further clarified that a cell is considered to have its height specified
-					if the cell or any of its table ancestor has a height specified in pixels or non-ignored percent. 
+					if the cell is considered to have its height specified explicitly
+					or the element is absolutely positioned, see <a href="http://www.w3.org/TR/CSS2/visudet.html#the-height-property">CSS 2</a>.
+				It is further clarified that 
+					a cell is considered to have its height specified explicitly
+					if the computed height of the cell or any of its table ancestors is a length or percentage. 
 			</div>
 
 			<div class="note">