Remove casting of invalid values

Previously, known boolean values were casted to `true`, and known
numerical values were casted to a number.  Even if those values
were invalid, which resulted in `NaN`.

Now, this is reverted and invalid booleans (not *overloaded* booleans)
are only casted to `true` when they have a valid value (empty or the
attribute’s name), and numeric values are only casted if they result
in a valid number.

Author: wooorm

index.js

@@ -47,11 +47,11 @@ function parsePrimitive(info, name, value) {
         return result;
     }
 
-    if (info.boolean) {
-        result = true;
-    } else if (info.numeric || info.positiveNumeric) {
-        result = Number(result);
-    } else if (info.overloadedBoolean) {
+    if (info.numeric || info.positiveNumeric) {
+        if (!isNaN(result)) {
+            result = Number(result);
+        }
+    } else if (info.boolean || info.overloadedBoolean) {
         /*
          * Accept `boolean` and `string`.
          */

test.js

@@ -248,7 +248,7 @@ test('hastscript', function (t) {
 
         st.deepEqual(
             h(null, {
-                'allowFullScreen': 'yup'
+                'allowFullScreen': ''
             }),
             {
                 'type': 'element',
@@ -258,7 +258,52 @@ test('hastscript', function (t) {
                 },
                 'children': []
             },
-            'should cast known `boolean` values'
+            'should cast valid known `boolean` values'
+        );
+
+        st.deepEqual(
+            h(null, {
+                'allowFullScreen': 'yup'
+            }),
+            {
+                'type': 'element',
+                'tagName': 'div',
+                'properties': {
+                    'allowFullScreen': 'yup'
+                },
+                'children': []
+            },
+            'should not cast invalid known `boolean` values'
+        );
+
+        st.deepEqual(
+            h(null, {
+                'volume': '0.1'
+            }),
+            {
+                'type': 'element',
+                'tagName': 'div',
+                'properties': {
+                    'volume': 0.1
+                },
+                'children': []
+            },
+            'should cast valid known `numeric` values'
+        );
+
+        st.deepEqual(
+            h(null, {
+                'volume': 'one'
+            }),
+            {
+                'type': 'element',
+                'tagName': 'div',
+                'properties': {
+                    'volume': 'one'
+                },
+                'children': []
+            },
+            'should not cast invalid known `numeric` values'
         );
 
         st.deepEqual(