[css-inline-3][css-page-3][css-text] Enforce non-negative value from …

…basic syntax

css-inline-3/Overview.bs

@@ -964,7 +964,7 @@ Line Spacing: the 'line-height' property</h3>
 
 	<pre class="propdef">
 	Name: line-height
-	Value: normal | <<number>> | <<length-percentage>>
+	Value: normal | <<number [0,∞]>> | <<length-percentage [0,∞]>>
 	Initial: normal
 	Applies to: non-replaced inline boxes and SVG <a>text content elements</a>
 	Inherited: yes
@@ -991,19 +991,19 @@ Line Spacing: the 'line-height' property</h3>
 			Determine the [=preferred line height=]
 			automatically based on font metrics.
 
-		<dt><dfn><<length>></dfn>
+		<dt><dfn><<length [0,∞]>></dfn>
 		<dd>
 			The specified length is used as the [=preferred line height=].
 			Negative values are illegal.
 
-		<dt><dfn><<number>></dfn>
+		<dt><dfn><<number [0,∞]>></dfn>
 		<dd>
 			The [=preferred line height=] is this number
 			multiplied by the element's computed 'font-size'.
 			Negative values are illegal.
 			The [=computed value=] is the same as the [=specified value=].
 
-		<dt><dfn><<percentage>></dfn>
+		<dt><dfn><<percentage [0,∞]>></dfn>
 		<dd>
 			The [=preferred line height=]
 			and [=computed value=] of the property

css-page-3/Overview.bs

@@ -1664,7 +1664,7 @@ Page size: the 'size' property</h3>
 	<pre class=descdef>
 	Name: size
 	For: @page
-	Value: <<length>>{1,2} | auto | [ <<page-size>> || [ portrait | landscape ] ]
+	Value: <<length [0,∞]>>{1,2} | auto | [ <<page-size>> || [ portrait | landscape ] ]
 	Initial: auto
 	Computed value: specified value, with <<length>>s made absolute.
 	</pre>
@@ -1748,7 +1748,7 @@ Page size: the 'size' property</h3>
 			shorter sides of the page box are horizontal. If a <<page-size>> is not specified, the size of the page sheet
 			is chosen by the UA.
 
-		<dt><dfn><<length>></dfn>
+		<dt><dfn><<length [0,∞]>></dfn>
 		<dd>
 			The page box will be set to the given absolute dimension(s). If only one length
 			value is specified, it sets both the width and height of the page box (i.e.,

css-text-3/Overview.bs

@@ -2856,7 +2856,7 @@ Tab Character Size: the 'tab-size' property</h3>
 
 	<pre class="propdef">
 	Name: tab-size
-	Value: <<number>> | <<length>>
+	Value: <<number [0,∞]>> | <<length [0,∞]>>
 	Initial: 8
 	Applies to: text
 	Inherited: yes

css-text-4/Overview.bs

@@ -4042,7 +4042,7 @@ Tab Character Size: the 'tab-size' property</h3>
 
 	<pre class="propdef">
 	Name: tab-size
-	Value: <<number>> | <<length>>
+	Value: <<number [0,∞]>> | <<length [0,∞]>>
 	Initial: 8
 	Applies to: text
 	Inherited: yes