[css-color-4] Correction to ray trace to avoid throwing off our intersection calculation

The suggested fix via #10579 (comment)
was not the ideal fix and artificially limited `tnear`. This is a
numerical instability issue and should be addressed as such by using an
epsilon compare to prevent rays that are too small.

Related #10579

Author: facelessuser

css-color-4/Overview.bs

@@ -6155,7 +6155,7 @@ Sample Pseudocode for the Ray Trace Gamut Mapping</h4>
 				<li>let |d| be |b| - |a|</li>
 				<li>let |direction|<i>[i]</i> be |d|</li>
 				<!--  Non parallel cases -->
-				<li>if (d != 0):
+				<li>if abs(|d|) < 1E-15
 					<ul>
 						<li>let |inv_d| be 1 / |d|</li>
 						<li>let |t1| be (|bmin|<i>[i]</i> - |a|) * |inv_d|</li>
@@ -6185,7 +6185,7 @@ Sample Pseudocode for the Ray Trace Gamut Mapping</h4>
 				</li>
 			</ul>
 		</li>
-		<li>if (|tnear| > 10)
+		<li>if |tnear| is infinite (or matches the initial very large value)
 			<ul>
 				<li>return INTERSECTION NOT FOUND</li>
 			</ul>