Fixed snippet URLs for sub-folders

app/assets/javascripts/snippets/components/edit.vue

@@ -90,7 +90,7 @@ export default {
       if (this.newSnippet) {
         return this.projectPath
           ? `${gon.relative_url_root}${this.projectPath}/-/snippets`
-          : `${gon.relative_url_root}-/snippets`;
+          : `${gon.relative_url_root}/-/snippets`;
       }
       return this.snippet.webUrl;
     },

app/assets/javascripts/snippets/components/snippet_header.vue

@@ -97,7 +97,7 @@ export default {
           text: __('New snippet'),
           href: this.snippet.project
             ? `${this.snippet.project.webUrl}/-/snippets/new`
-            : `${gon.relative_url_root}-/snippets/new`,
+            : `${gon.relative_url_root}/-/snippets/new`,
           variant: 'success',
           category: 'secondary',
           cssClass: 'ml-2',

spec/frontend/snippets/components/edit_spec.js

@@ -200,7 +200,7 @@ describe('Snippet Edit app', () => {
 
     it.each`
       projectPath       | snippetArg               | expectation
-      ${''}             | ${[]}                    | ${`${relativeUrlRoot}-/snippets`}
+      ${''}             | ${[]}                    | ${`${relativeUrlRoot}/-/snippets`}
       ${'project/path'} | ${[]}                    | ${`${relativeUrlRoot}project/path/-/snippets`}
       ${''}             | ${[createTestSnippet()]} | ${TEST_WEB_URL}
       ${'project/path'} | ${[createTestSnippet()]} | ${TEST_WEB_URL}