[css-values-4] Add some more term anchors for value combination, at least temporarily.

Author: fantasai

css-values-4/Overview.bs

@@ -352,7 +352,7 @@ Combining Values: Interpolation, Addition, and Accumulation</h2>
 	are defined:
 
 	<dl export>
-		<dt><dfn id="interpolation" lt="interpolation | interpolate | value interpolation">interpolation</dfn>
+		<dt><dfn id="interpolation" lt="interpolation | interpolate | value interpolation | interpolation procedure">interpolation</dfn>
 		<dd>
 			Given two property values
 			<var>V<sub>a</sub></var> and <var>V<sub>B</sub></var>,
@@ -369,7 +369,7 @@ Combining Values: Interpolation, Addition, and Accumulation</h2>
 			As a result, this procedure must also define
 			extrapolation behavior for <var>p</var> outside [0, 1].
 
-		<dt><dfn id="addition" lt="value addition" local-lt="add | addition">addition</dfn>
+		<dt><dfn id="addition" lt="value addition | addition procedure" local-lt="add | addition">addition</dfn>
 		<dd>
 			Given two property values
 			<var>V<sub>a</sub></var> and <var>V<sub>B</sub></var>,
@@ -391,7 +391,7 @@ Combining Values: Interpolation, Addition, and Accumulation</h2>
 			decomposing and interpolating the matrix components
 			whilst addition relies on matrix multiplication.
 
-		<dt><dfn id="accumulation" lt="value accumulation" local-lt="accumulate | accumulation">accumulation</dfn>
+		<dt><dfn id="accumulation" lt="value accumulation | accumulation procedure" local-lt="accumulate | accumulation">accumulation</dfn>
 		<dd>
 			Given two property values
 			<var>V<sub>a</sub></var> and <var>V<sub>B</sub></var>,