fix(compiler-ssr): avoid duplicated asset imports merged from component slot client branch

fix vitejs/vite#2034

packages/compiler-core/src/transform.ts

@@ -89,7 +89,7 @@ export interface TransformContext
   components: Set<string>
   directives: Set<string>
   hoists: (JSChildNode | null)[]
-  imports: Set<ImportItem>
+  imports: ImportItem[]
   temps: number
   cached: number
   identifiers: { [name: string]: number | undefined }
@@ -163,7 +163,7 @@ export function createTransformContext(
     components: new Set(),
     directives: new Set(),
     hoists: [],
-    imports: new Set(),
+    imports: [],
     constantCache: new Map(),
     temps: 0,
     cached: 0,
@@ -293,7 +293,7 @@ export function transform(root: RootNode, options: TransformOptions) {
   root.helpers = [...context.helpers]
   root.components = [...context.components]
   root.directives = [...context.directives]
-  root.imports = [...context.imports]
+  root.imports = context.imports
   root.hoists = context.hoists
   root.temps = context.temps
   root.cached = context.cached