Add operator<< to StyleDifference for debug logging.

third_party/WebKit/Source/core/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/chromecast_build.gni")
 import("//build/toolchain/toolchain.gni")
 import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//testing/libfuzzer/fuzzer_test.gni")
 import("//third_party/WebKit/Source/bindings/bindings.gni")
@@ skipping 1368 matching lines @@
     "paint/StubChromeClientForSPv2.h",
     "paint/TableCellPainterTest.cpp",
     "paint/TextPainterTest.cpp",
     "paint/VideoPainterTest.cpp",
     "streams/ReadableStreamOperationsTest.cpp",
     "style/BorderValueTest.cpp",
     "style/ComputedStyleTest.cpp",
     "style/FilterOperationsTest.cpp",
     "style/OutlineValueTest.cpp",
     "style/SVGComputedStyleTest.cpp",
+    "style/StyleDifferenceTest.cpp",
     "svg/SVGPathParserTest.cpp",
     "svg/UnsafeSVGAttributeSanitizationTest.cpp",
     "svg/graphics/SVGImageTest.cpp",
     "timing/MemoryInfoTest.cpp",
     "timing/PerformanceBaseTest.cpp",
     "timing/PerformanceObserverTest.cpp",
     "timing/PerformanceTest.cpp",
     "workers/DedicatedWorkerTest.cpp",
     "workers/MainThreadWorkletTest.cpp",
     "workers/ThreadedWorkletTest.cpp",
@@ skipping 48 matching lines @@
   sources = [
     "frame/csp/ContentSecurityPolicyFuzzer.cpp",
   ]
   deps = [
     ":core",
     "//third_party/WebKit/Source/platform:blink_fuzzer_test_support",
   ]
   dict = "//testing/libfuzzer/fuzzers/dicts/content_security_policy.dict"
   seed_corpus = "//testing/libfuzzer/fuzzers/content_security_policy_corpus"
 }