patch 8.2.4925: trailing backslash may cause reading past end of line

Problem:    Trailing backslash may cause reading past end of line.
Solution:   Check for NUL after backslash.

src/testdir/test_textobjects.vim

@@ -185,10 +185,18 @@ func Test_string_html_objects()
     call assert_equal("<div><div\nattr=\"attr\"\n></div></div>", @", e)
 
     set quoteescape&
+
+    " this was going beyond the end of the line
+    %del
+    sil! norm i"\
+    sil! norm i"\
+    sil! norm i"\
+    call assert_equal('"\', getline(1))
+
+    bwipe!
   endfor
 
   set enc=utf-8
-  bwipe!
 endfunc
 
 func Test_empty_html_tag()

src/textobject.c

@@ -1664,7 +1664,11 @@ find_next_quote(
 	if (c == NUL)
 	    return -1;
 	else if (escape != NULL && vim_strchr(escape, c))
+	{
 	    ++col;
+	    if (line[col] == NUL)
+		return -1;
+	}
 	else if (c == quotechar)
 	    break;
 	if (has_mbyte)

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4925,
 /**/
     4924,
 /**/