Fixed first newline not working

app/assets/javascripts/lib/utils/text_utility.js

@@ -44,8 +44,15 @@
       }
     };
     gl.text.insertText = function(textArea, text, tag, blockTag, selected, wrap) {
-      var insertText, inserted, selectedSplit, startChar, removedLastNewLine;
+      var insertText, inserted, selectedSplit, startChar, removedLastNewLine, removedFirstNewLine;
       removedLastNewLine = false;
+      removedFirstNewLine = false;
+
+      // Remove the first newline
+      if (selected.indexOf('\n') === 0) {
+        removedFirstNewLine = true;
+        selected = selected.replace(/\n+/, '');
+      }
       // Remove the last newline
       if (textArea.selectionEnd - textArea.selectionStart > selected.replace(/\n$/, '').length) {
@@ -72,6 +79,10 @@
         insertText = "" + startChar + tag + selected + (wrap ? tag : ' ');
       }
+      if (removedFirstNewLine) {
+        insertText = '\n' + insertText;
+      }
+
       if (removedLastNewLine) {
         insertText += '\n';
       }

spec/features/issues/markdown_toolbar_spec.rb

+require 'rails_helper'
+
+feature 'Issue markdown toolbar', feature: true, js: true do
+  let(:project) { create(:project, :public) }
+  let(:issue)   { create(:issue, project: project) }
+  let(:user)   { create(:user) }
+
+  before do
+    login_as(user)
+
+    visit namespace_project_issue_path(project.namespace, project, issue)
+  end
+
+  it "doesn't include first new line when adding bold" do
+    find('#note_note').native.send_keys('test')
+    find('#note_note').native.send_key(:enter)
+    find('#note_note').native.send_keys('bold')
+
+    page.evaluate_script('document.getElementById("note_note").setSelectionRange(4, 9)')
+
+    first('.toolbar-btn').click
+
+    expect(find('#note_note')[:value]).to eq("test\n**bold**\n")
+  end
+
+  it "doesn't include first new line when adding underline" do
+    find('#note_note').native.send_keys('test')
+    find('#note_note').native.send_key(:enter)
+    find('#note_note').native.send_keys('underline')
+
+    page.evaluate_script('document.getElementById("note_note").setSelectionRange(4, 50)')
+
+    find('.toolbar-btn:nth-child(2)').click
+
+    expect(find('#note_note')[:value]).to eq("test\n*underline*\n")
+  end
+end