Make the snippet contribution point dynamic

src/vs/workbench/parts/snippets/electron-browser/snippetsService.ts

@@ -107,6 +107,7 @@ namespace snippetExt {
 	};
 
 	export const point = ExtensionsRegistry.registerExtensionPoint<snippetExt.ISnippetsExtensionPoint[]>({
+		isDynamic: true,
 		extensionPoint: 'snippets',
 		deps: [languagesExtPoint],
 		jsonSchema: snippetExt.snippetsContribution
@@ -207,6 +208,13 @@ class SnippetsService implements ISnippetsService {
 
 	private _initExtensionSnippets(): void {
 		snippetExt.point.setHandler(extensions => {
+
+			this._files.forEach((value, key) => {
+				if (value.source === SnippetSource.Extension) {
+					this._files.delete(key);
+				}
+			});
+
 			for (const extension of extensions) {
 				for (const contribution of extension.value) {
 					const validContribution = snippetExt.toValidSnippet(extension, contribution, this._modeService);