FIX: blockquote button implementation

Previously clicking on blockquote in the middle of sentence
would result in incorrect formatting

app/assets/javascripts/discourse/components/d-editor.js.es6

@@ -78,7 +78,7 @@ class Toolbar {
       group: 'insertions',
       icon: 'quote-right',
       shortcut: 'Shift+9',
-      perform: e => e.applySurround('> ', '', 'code_text')
+      perform: e => e.applyList('> ', 'blockquote_text')
     });
 
     this.addButton({id: 'code', group: 'insertions', shortcut: 'Shift+C', action: 'formatCode'});

config/locales/client.en.yml

@@ -1129,6 +1129,7 @@ en:
       options: "Options"
       whisper: "whisper"
       unlist: "unlisted"
+      blockquote_text: "Blockquote"
 
       add_warning: "This is an official warning."
       toggle_whisper: "Toggle Whisper"

test/javascripts/components/d-editor-test.js.es6

@@ -515,29 +515,37 @@ third line`
 
 
 testCase('quote button', function(assert, textarea) {
-  click('button.quote');
-  andThen(() => {
-    assert.equal(this.get('value'), 'hello world.');
-  });
 
   andThen(() => {
     textarea.selectionStart = 6;
-    textarea.selectionEnd = 11;
+    textarea.selectionEnd = 9;
   });
 
   click('button.quote');
   andThen(() => {
-    assert.equal(this.get('value'), 'hello > world.');
-    assert.equal(textarea.selectionStart, 6);
-    assert.equal(textarea.selectionEnd, 13);
+    assert.equal(this.get('value'), 'hello\n\n> wor\n\nld.');
+    assert.equal(textarea.selectionStart, 7);
+    assert.equal(textarea.selectionEnd, 12);
+  });
+
+  click('button.quote');
+
+  andThen(() => {
+    assert.equal(this.get('value'), 'hello\n\nwor\n\nld.');
+    assert.equal(textarea.selectionStart, 7);
+    assert.equal(textarea.selectionEnd, 10);
+  });
+
+  andThen(() => {
+    textarea.selectionStart = 15;
+    textarea.selectionEnd = 15;
   });
 
   click('button.quote');
   andThen(() => {
-    assert.equal(this.get('value'), 'hello world.');
-    assert.equal(textarea.selectionStart, 6);
-    assert.equal(textarea.selectionEnd, 11);
+    assert.equal(this.get('value'), 'hello\n\nwor\n\nld.\n\n> Blockquote');
   });
+
 });
 
 testCase(`bullet button with no selection`, function(assert, textarea) {