LibWeb: Limit `HTMLProgressElement.max` to positive values

Previously, 0 was returned if `HTMLProgressElement.max` was set to a
negative value.

Tests/LibWeb/Text/expected/HTML/HTMLProgressElement-set-attributes.txt

@@ -2,6 +2,7 @@ value attribute initial value: 0
 max attribute initial value: 1
 value attribute after setting value attribute to -1: 0
 max attribute after setting max attribute to -1: 1
+max attribute after setting max attribute to 0: 1
 value attribute after setting value attribute to 50: 1
 value attribute after setting max attribute to 100: 50
 max attribute after setting max attribute to 100: 100

Tests/LibWeb/Text/input/HTML/HTMLProgressElement-set-attributes.html

@@ -9,6 +9,8 @@
         println(`value attribute after setting value attribute to -1: ${progressElement.value}`);
         progressElement.max = -1;
         println(`max attribute after setting max attribute to -1: ${progressElement.max}`);
+        progressElement.max = 0;
+        println(`max attribute after setting max attribute to 0: ${progressElement.max}`);
         progressElement.value = 50;
         println(`value attribute after setting value attribute to 50: ${progressElement.value}`);
         progressElement.max = 100;

Userland/Libraries/LibWeb/HTML/HTMLProgressElement.cpp

@@ -64,7 +64,8 @@ double HTMLProgressElement::max() const
 {
     if (auto max_string = get_attribute(HTML::AttributeNames::max); max_string.has_value()) {
         if (auto max = parse_floating_point_number(*max_string); max.has_value())
-            return AK::max(*max, 0);
+            if (*max > 0)
+                return *max;
     }
     return 1;
 }