[css-color-4] Add example, wpt for resolving currentColor w3c#1510

Author: svgeesus

css-color-4/Overview.bs

@@ -5467,6 +5467,42 @@ Resolving values of the ''color()'' function</h3>
 	not as the value of the 'color' property,
 	so descendants will use their own 'color' property to resolve it.
 
+	<div class="example" id="ex-currentcolor-resolve">
+		For example, given this html:
+
+		<pre class="lang-html">
+			&lt;div>
+				&lt;p>Assume this example text is long enough
+					to wrap on multiple lines.
+				&lt;/p>
+			&lt;/div>
+		</pre>
+
+		and this css:
+
+		<pre class="lang-css">
+			div {
+				color: <span class="swatch" style="--color: forestgreen"></span> forestgreen;
+				text-shadow: currentColor;
+			}
+			p {
+				color: <span class="swatch" style="--color: mediumseagreen"></span> mediumseagreen;
+			} 
+			p::firstline {
+				color: <span class="swatch" style="--color: yellowgreen"></span> yellowgreen;
+			}
+		</pre>
+
+		The value of the inherited property text-shadow 
+		on the first line fragment would be yellowgreen.
+	</div>
+
+	<wpt>
+		currentcolor-001.html
+		currentcolor-002.html
+		currentcolor-003.html
+	</wpt>
+
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