AK: Don’t drop lines between \r and \n in StringView::lines() (#7662)

StringView::lines() supports line-separators “\n”, “\r”, and “\r\n”.
The method will drop an entire line if it is surrounded by “\r”
and “\n” separators on the left and right sides respectively.

AK/StringView.cpp

@@ -99,12 +99,13 @@ Vector<StringView> StringView::lines(bool consider_cr) const
             if (last_ch_was_cr) {
                 substart = i + 1;
                 split_view = false;
-                last_ch_was_cr = false;
             }
         }
         if (ch == '\r') {
             split_view = true;
             last_ch_was_cr = true;
+        } else {
+            last_ch_was_cr = false;
         }
         if (split_view) {
             size_t sublen = i - substart;

Tests/AK/TestStringView.cpp

@@ -77,7 +77,7 @@ TEST_CASE(ends_with)
 
 TEST_CASE(lines)
 {
-    String test_string = "a\nb\r\nc\rd";
+    String test_string = "a\rb\nc\r\nd";
     StringView test_string_view = test_string.view();
     Vector<StringView> test_string_vector = test_string_view.lines();
     EXPECT_EQ(test_string_vector.size(), 4u);