fix form default submit behavior.

src/components/form/form.vue

@@ -1,5 +1,7 @@
 <template>
-    <form :class="classes"><slot></slot></form>
+    <form :class="classes" @submit="formSubmit">
+        <slot></slot>
+    </form>
 </template>
 <script>
     // https://github.com/ElemeFE/element/blob/dev/packages/form/src/form.vue
@@ -75,6 +77,9 @@
                 if (!field) { throw new Error('[iView warn]: must call validateField with valid prop string!'); }
 
                 field.validate('', cb);
+            },
+            formSubmit(event){
+                event.preventDefault();
             }
         },
         watch: {
@@ -93,4 +98,4 @@
             });
         }
     };
-</script>
+</script>