Support Svelte 3

fixes #546, #551, #552, #554

test/apps/preloading/src/routes/_layout.html

@@ -1,15 +1,20 @@
-{#if preloading}
+<script context="module">
+	export function preload() {
+		return {
+			rootPreloadFunctionRan: true
+		};
+	}
+</script>
+
+<script>
+	import { preloading } from '@sapper/app';
+
+	export let child;
+	export let rootPreloadFunctionRan;
+</script>
+
+{#if $preloading}
 	<progress class='preloading-progress' value=0.5/>
 {/if}
 
-<svelte:component this={child.component} {rootPreloadFunctionRan} {...child.props}/>
-
-<script>
-	export default {
-		preload() {
-			return {
-				rootPreloadFunctionRan: true
-			};
-		}
-	};
-</script>
+<svelte:component this={child.component} {rootPreloadFunctionRan} {...child.props}/>

test/apps/preloading/src/routes/prefetch/[slug]/index.html

@@ -1 +1,5 @@
-<h1>{params.slug}</h1>
+<script>
+	import { page } from '@sapper/app';
+</script>
+
+<h1>{$page.params.slug}</h1>

test/apps/preloading/src/routes/preload-values/custom-class.html

@@ -1,17 +1,19 @@
-<h1>{foo.bar()}</h1>
+<script context="module">
+	export function preload() {
+		class Foo {
+			bar() {
+				return 42;
+			}
+		}
+
+		return {
+			foo: new Foo()
+		};
+	}
+</script>
 
 <script>
-	export default {
-		preload() {
-			class Foo {
-				bar() {
-					return 42;
-				}
-			}
+	export let foo;
+</script>
 
-			return {
-				foo: new Foo()
-			};
-		}
-	};
-</script>
+<h1>{foo.bar()}</h1>

test/apps/preloading/src/routes/preload-values/set.html

@@ -1,11 +1,13 @@
-<h1>{set.has('x')}</h1>
+<script context="module">
+	export function preload() {
+		return {
+			set: new Set(['x'])
+		};
+	}
+</script>
 
 <script>
-	export default {
-		preload() {
-			return {
-				set: new Set(['x'])
-			};
-		}
-	};
-</script>
+	export let set;
+</script>
+
+<h1>{set.has('x')}</h1>

test/apps/preloading/src/routes/slow-preload.html

@@ -1,15 +1,13 @@
-<h1>This page should never render</h1>
+<script context="module">
+	export function preload() {
+		return new Promise(fulfil => {
+			if (typeof window !== 'undefined') {
+				window.fulfil = fulfil;
+			} else {
+				fulfil({});
+			}
+		});
+	}
+</script>
 
-<script>
-	export default {
-		preload() {
-			return new Promise(fulfil => {
-				if (typeof window !== 'undefined') {
-					window.fulfil = fulfil;
-				} else {
-					fulfil({});
-				}
-			});
-		}
-	};
-</script>
+<h1>This page should never render</h1>