LibWeb: Extend meter test

Author: https://github.com/simonkrauter
Commit: https://github.com/LadybirdBrowser/ladybird/commit/cbc4832a53
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/474
Issue: https://github.com/LadybirdBrowser/ladybird/issues/473
Reviewed-by: https://github.com/tcl3

Tests/LibWeb/Ref/meter.html

@@ -15,3 +15,5 @@
 <meter low="4" high="6" value="9" max="10" optimum="1"></meter>
 <meter low="4" value="1" high="5" min="3" max="10" optimum="10"></meter>
 <meter low="4" value="3" high="5" min="1" max="2" optimum="10"></meter>
+<meter min="1" low="2" high="5" optimum="7" max="10" value="6"></meter>
+<meter min="1" low="2" high="5" optimum="7" max="10" value="8"></meter>