Fix #56

Author: mganss

src/AngleSharp.Css.Tests/Declarations/CssFontProperty.cs

@@ -677,5 +677,17 @@ public void CssFontStyleWeightSizeHeightFamiliesLegal()
             Assert.IsTrue(property.HasValue);
             Assert.AreEqual("italic bold 12px / 30px Georgia, serif", property.Value);
         }
+
+        [Test]
+        public void CssFontStyleNumericWeightSizeFamiliesLegal()
+        {
+            var snippet = "font: 400 12px Georgia, serif";
+            var property = ParseDeclaration(snippet);
+            Assert.AreEqual("font", property.Name);
+            Assert.IsFalse(property.IsImportant);
+            Assert.IsFalse(property.IsInherited);
+            Assert.IsTrue(property.HasValue);
+            Assert.AreEqual("400 12px Georgia, serif", property.Value);
+        }
     }
 }

src/AngleSharp.Css/Declarations/FontDeclaration.cs

@@ -60,7 +60,7 @@ public ICssValue Convert(StringSource source)
 
                     if (weight == null)
                     {
-                        weight = source.ParseConstant(Map.FontWeights);
+                        weight = FontWeightDeclaration.Converter.Convert(source);
                         source.SkipSpacesAndComments();
                     }