LibGfx/WOFF2: Tolerate incorrect totalSfntSize in WOFF2 header

The specification says that this value is for reference only, so we
should be able to load a file where this value is incorrect.

Tests/LibGfx/CMakeLists.txt

@@ -10,6 +10,7 @@ set(TEST_SOURCES
     TestRect.cpp
     TestScalingFunctions.cpp
     TestWOFF.cpp
+    TestWOFF2.cpp
 )
 
 foreach(source IN LISTS TEST_SOURCES)

Tests/LibGfx/TestWOFF2.cpp

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2023, Tim Ledbetter <timledbetter@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibGfx/Font/WOFF2/Font.h>
+#include <LibTest/TestCase.h>
+
+#ifdef AK_OS_SERENITY
+#    define TEST_INPUT(x) ("/usr/Tests/LibGfx/test-inputs/" x)
+#else
+#    define TEST_INPUT(x) ("test-inputs/" x)
+#endif
+
+TEST_CASE(tolerate_incorrect_sfnt_size)
+{
+    auto file = MUST(Core::MappedFile::map(TEST_INPUT("woff2/incorrect_sfnt_size.woff2"sv)));
+    auto font = TRY_OR_FAIL(WOFF2::Font::try_load_from_externally_owned_memory(file->bytes()));
+    EXPECT_EQ(font->family(), "Test"_string);
+    EXPECT_EQ(font->glyph_count(), 4u);
+}