Editor: Unindent backpace mode should not apply for parag. separators

QChar:isSpace also includes paragraph separator, for which the backspace
behavior should be the normal one.

Change-Id: I80c362a4e11b436259f85fea4c73de874fc64249
Reviewed-on: http://codereview.qt-project.org/5389Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: hjk <qthjk@ovi.com>

src/plugins/texteditor/basetexteditor.cpp

@@ -4513,9 +4513,12 @@ void BaseTextEditorWidget::handleHomeKey(bool anchor)
 void BaseTextEditorWidget::handleBackspaceKey()
 {
     QTextCursor cursor = textCursor();
-    int pos = cursor.position();
     QTC_ASSERT(!cursor.hasSelection(), return);
 
+    const int pos = cursor.position();
+    if (!pos)
+        return;
+
     bool cursorWithinSnippet = false;
     if (d->m_snippetOverlay->isVisible()) {
         QTextCursor snippetCursor = cursor;
@@ -4570,7 +4573,8 @@ void BaseTextEditorWidget::handleBackspaceKey()
             }
         }
     } else if (tabSettings.m_smartBackspaceBehavior == TabSettings::BackspaceUnindents) {
-        if (!pos || !characterAt(pos - 1).isSpace()) {
+        const QChar &c = characterAt(pos - 1);
+        if (!(c == QLatin1Char(' ') || c == QLatin1Char('\t'))) {
             if (cursorWithinSnippet)
                 cursor.beginEditBlock();
             cursor.deletePreviousChar();