fix(runtime-dom): style binding multi value support

fix #1759

packages/runtime-dom/__tests__/patchStyle.spec.ts

@@ -74,6 +74,7 @@ describe(`runtime-dom: style patching`, () => {
     const store: any = {}
     return {
       style: {
+        display: '',
         WebkitTransition: '',
         setProperty(key: string, val: string) {
           store[key] = val
@@ -96,4 +97,15 @@ describe(`runtime-dom: style patching`, () => {
     patchProp(el as any, 'style', {}, { transition: 'all 1s' })
     expect(el.style.WebkitTransition).toBe('all 1s')
   })
+
+  it('multiple values', () => {
+    const el = mockElementWithStyle()
+    patchProp(
+      el as any,
+      'style',
+      {},
+      { display: ['-webkit-box', '-ms-flexbox', 'flex'] }
+    )
+    expect(el.style.display).toBe('flex')
+  })
 })