fix import statment completion hack sourcemap (#1131)

Author: jasonlyu123

packages/svelte2tsx/src/svelte2tsx/processInstanceScriptContent.ts

@@ -14,6 +14,7 @@ import { handleTypeAssertion } from './nodes/handleTypeAssertion';
 import { ImplicitStoreValues } from './nodes/ImplicitStoreValues';
 import { Generics } from './nodes/Generics';
 import { is$$SlotsDeclaration } from './nodes/slot';
+import { preprendStr } from '../utils/magic-string';
 
 export interface InstanceScriptProcessResult {
     exportedNames: ExportedNames;
@@ -291,7 +292,7 @@ export function processInstanceScriptContent(
             const end = node.getEnd() + astOffset;
 
             if (str.original[end - 1] !== ';') {
-                str.appendLeft(end, ';');
+                preprendStr(str, end, ';');
             }
         }
 

packages/svelte2tsx/test/sourcemaps/samples/import-equal/input.svelte

@@ -0,0 +1,4 @@
+<script>
+    import A
+    import C = require('');
+</script>

packages/svelte2tsx/test/sourcemaps/samples/import-equal/mappings.jsx

@@ -0,0 +1,30 @@
+///<reference types="svelte" />
+//----------------------------------------------------------------------------------------------------------------------------------------------------
+<></>;function render() {                                                                                                                             {/**
+=#                            Originless mappings                                                                                                     
+<></>;function•render()•{↲    [generated] line 2                                                                                                      
+  <   s                                                                                                                                               
+<s                                                                                                                                                    
+<script>↲                     [original] line 1 (rest generated at line 3)                                                                            
+------------------------------------------------------------------------------------------------------------------------------------------------------ */}
+                                                                                                                                                      {/**
+↲            [generated] line 3                                                                                                                       
+        ↲                                                                                                                                             
+<script>↲    [original] line 1 (rest generated at line 2)                                                                                             
+------------------------------------------------------------------------------------------------------------------------------------------------------ */}
+    import A;                                                                                                                                         {/**
+••••import•A;↲    [generated] line 4                                                                                                                  
+••••import•A↲     [original] line 2                                                                                                                   
+------------------------------------------------------------------------------------------------------------------------------------------------------ */}
+    import C = require('');                                                                                                                           {/**
+------------------------------------------------------------------------------------------------------------------------------------------------------ */}
+;                                                                                                                                                     {/**
+;↲           [generated] line 6                                                                                                                       
+<                                                                                                                                                     
+</script>    [original] line 4                                                                                                                        
+------------------------------------------------------------------------------------------------------------------------------------------------------ */}
+() => (<></>);
+return { props: {}, slots: {}, getters: {}, events: {} }}
+
+export default class Input__SvelteComponent_ extends __sveltets_1_createSvelte2TsxComponent(__sveltets_1_partial(__sveltets_1_with_any_event(render()))) {
+}

packages/svelte2tsx/test/sourcemaps/samples/import-equal/test.jsx

@@ -0,0 +1,2 @@
+/** tested-ranges: [] */
+/** origin-hash: 2qcima */