test: 调整测试例规避iOS safari表现不一致的问题

如果父元素设置了`overflow-y: auto; -webkit-overflow-scrolling: touch;`样式，那么他的自元素即使是fixed也会受overflow属性影响而无法显示

pages/CSS/layout/position.uvue

@@ -4,15 +4,15 @@
     <!-- #endif -->
     <view style="flex-grow: 1">
       <view>
-        <text>position: relative</text>
+        <text>position: fixed</text>
         <scroll-view
           style="width: 250px; height: 250px; background-color: gray"
         >
           <view
             style="width: 50px; height: 50px; background-color: red"
           ></view>
-          <view class="common" style="position: relative">
-            <text class="text">relative</text>
+          <view class="common fixed" style="position: fixed">
+            <text class="text">fixed</text>
           </view>
           <view
             style="width: 50px; height: 50px; background-color: blue"
@@ -39,15 +39,15 @@
       </view>
 
       <view>
-        <text>position: absolute</text>
+        <text>position: relative</text>
         <scroll-view
           style="width: 250px; height: 250px; background-color: gray"
         >
           <view
             style="width: 50px; height: 50px; background-color: red"
           ></view>
-          <view class="common" style="position: absolute">
-            <text class="text">absolute</text>
+          <view class="common" style="position: relative">
+            <text class="text">relative</text>
           </view>
           <view
             style="width: 50px; height: 50px; background-color: blue"
@@ -74,15 +74,15 @@
       </view>
 
       <view>
-        <text>position: fixed</text>
+        <text>position: absolute</text>
         <scroll-view
           style="width: 250px; height: 250px; background-color: gray"
         >
           <view
             style="width: 50px; height: 50px; background-color: red"
           ></view>
-          <view class="common fixed" style="position: fixed">
-            <text class="text">fixed</text>
+          <view class="common" style="position: absolute">
+            <text class="text">absolute</text>
           </view>
           <view
             style="width: 50px; height: 50px; background-color: blue"
@@ -107,7 +107,8 @@
           ></view>
         </scroll-view>
       </view>
-    </view>
+
+      </view>
     <!-- #ifdef APP -->
   </scroll-view>
   <!-- #endif -->