spellcheck: Drop use of deprecated sci_get_text_range()

Naive replacement leads to allocating the buffer on each call, but it
should not be a concern as the previous commit dropped more useless
allocations yet nobody complained before.

spellcheck/src/speller.c

@@ -206,7 +206,6 @@ gint sc_speller_process_line(GeanyDocument *doc, gint line_number)
 	gint suggestions_found = 0;
 	gint wordchars_len;
 	gchar *wordchars;
-	GString *str;
 
 	g_return_val_if_fail(sc_speller_dict != NULL, 0);
 	g_return_val_if_fail(doc != NULL, 0);
@@ -223,35 +222,32 @@ gint sc_speller_process_line(GeanyDocument *doc, gint line_number)
 		scintilla_send_message(doc->editor->sci, SCI_SETWORDCHARS, 0, (sptr_t)wordchars);
 	}
 
-	str = g_string_sized_new(256);
-
 	pos_start = sci_get_position_from_line(doc->editor->sci, line_number);
 	pos_end = sci_get_position_from_line(doc->editor->sci, line_number + 1);
 
 	while (pos_start < pos_end)
 	{
+		gchar *word;
+
 		wstart = scintilla_send_message(doc->editor->sci, SCI_WORDSTARTPOSITION, pos_start, TRUE);
 		wend = scintilla_send_message(doc->editor->sci, SCI_WORDENDPOSITION, wstart, FALSE);
 		if (wstart == wend)
 			break;
 
-		/* ensure the string has enough allocated memory */
-		if (str->len < (guint)(wend - wstart))
-			g_string_set_size(str, wend - wstart);
-
-		sci_get_text_range(doc->editor->sci, wstart, wend, str->str);
+		word = sci_get_contents_range(doc->editor->sci, wstart, wend);
 
-		suggestions_found += sc_speller_check_word(doc, line_number, str->str, wstart, wend);
+		suggestions_found += sc_speller_check_word(doc, line_number, word, wstart, wend);
 
 		pos_start = wend + 1;
+
+		g_free(word);
 	}
 
 	/* reset wordchars for the current document */
 	wordchars[wordchars_len] = '\0';
 	scintilla_send_message(doc->editor->sci, SCI_SETWORDCHARS, 0, (sptr_t)wordchars);
 
 	g_free(wordchars);
-	g_string_free(str, TRUE);
 	return suggestions_found;
 }