Some javafx.web files are missing GPLv2+Classpath copyright header

While updating the copyright year to 2018 to fix JDK-8201563 I noticed a few files that have a simple copyright header without any specific license terms. These should have a GPLv2+Classpath exception copyright header.

A partial list of files is below, but this is almost certainly incomplete:

modules/javafx.web/src/main/native/Source/WTF/wtf/java/MainThreadJava.cpp
modules/javafx.web/src/main/native/Source/WTF/wtf/java/StringJava.cpp
modules/javafx.web/src/main/native/Source/WebCore/bridge/jni/jsc/BridgeUtils.h
modules/javafx.web/src/main/native/Source/WebCore/page/java/DragControllerJava.cpp
modules/javafx.web/src/main/native/Source/WebCore/page/java/EventHandlerJava.cpp
modules/javafx.web/src/main/native/Source/WebCore/platform/network/java/CookieJarJava.cpp
modules/javafx.web/src/main/native/Source/WebCore/platform/network/java/ResourceHandleJava.cpp
modules/javafx.web/src/main/native/Source/WebCore/platform/network/java/ResourceRequestJava.cpp
modules/javafx.web/src/main/native/Source/WebCore/platform/network/java/ResourceResponse.h
modules/javafx.web/src/main/native/Source/WebCore/platform/network/java/URLLoader.cpp
modules/javafx.web/src/main/native/Tools/DumpRenderTree/java/JavaEnv.cpp
modules/javafx.web/src/main/native/Tools/DumpRenderTree/java/JavaEnv.h
modules/javafx.web/src/main/native/Tools/DumpRenderTree/java/TestRunnerJava.cpp
modules/javafx.web/src/main/native/Tools/DumpRenderTree/java/WorkQueueItemJava.cpp