fix(compiler-core): fix v-if block handling for components that fail to resolve

fix #2058

packages/compiler-core/__tests__/transforms/vIf.spec.ts

@@ -93,10 +93,12 @@ describe('compiler: v-if', () => {
       expect((node.branches[0].children[0] as ElementNode).tagType).toBe(
         ElementTypes.COMPONENT
       )
+      // #2058 since a component may fail to resolve and fallback to a plain
+      // element, it still needs to be made a block
       expect(
         ((node.branches[0].children[0] as ElementNode)!
           .codegenNode as VNodeCall)!.isBlock
-      ).toBe(false)
+      ).toBe(true)
     })
 
     test('v-if + v-else', () => {