Fix crash in {#await} on ts (#33)

Author: ota-meshi

package.json

@@ -36,6 +36,7 @@
     },
     "homepage": "https://github.com/ota-meshi/svelte-eslint-parser#readme",
     "dependencies": {
+        "eslint-scope": "^5.1.1",
         "eslint-visitor-keys": "^2.0.0",
         "espree": "^7.3.1",
         "lodash": "^4.17.20"

src/context/script-let.ts

@@ -360,7 +360,7 @@ export class ScriptLetContext {
                     range,
                 })
                 if (this.ctx.isTypeScript()) {
-                    source += ` as (${typings![index]})`
+                    source += ` : (${typings![index]})`
                 }
             }
             const restore = this.appendScript(

tests/fixtures/parser/ast/ts-promise01-input.svelte

@@ -0,0 +1,11 @@
+<script lang="ts">
+	let promise:Promise<{a:number}> = new Promise((resolve)=>resolve({a:42}));
+</script>
+
+{#await promise}
+	<p>...waiting</p>
+{:then number}
+	<p>The number is {number.a}</p>
+{:catch error}
+	<p style="color: red">{error.message}</p>
+{/await}