[Content Filtering] Adopt new NEFilterSource SPI

[Content Filtering] Adopt new NEFilterSource SPI
https://bugs.webkit.org/show_bug.cgi?id=142710
rdar://problem/19023855

Reviewed by Dan Bernstein.

Teach NetworkExtensionContentFilter to use a new, alternate NEFilterSource SPI on platforms where it is available.

* platform/ContentFilter.cpp:
(WebCore::ContentFilter::types): Renamed HAVE(NE_FILTER_SOURCE) to HAVE(NETWORK_EXTENSION).
* platform/cocoa/NetworkExtensionContentFilter.h: Renamed member variables to remove redundancy, forward-declared NEFilterSourceStatus,
added a dispatch_semaphore member variable to avoid creating and destroying multiple semaphores, and made m_originalData a SharedBuffer.
* platform/cocoa/NetworkExtensionContentFilter.mm:
(decisionInfoReplacementData): Returned the replacement data from a decision handler info dictionary.
(WebCore::createNEFilterSource): Created either an old-style or new-style NEFilterSource object.
(WebCore::NetworkExtensionContentFilter::NetworkExtensionContentFilter): Called receivedResponse:decisionHandler: when using the new SPI.
(WebCore::NetworkExtensionContentFilter::~NetworkExtensionContentFilter): Released the dispatch_semaphore.
(WebCore::NetworkExtensionContentFilter::addData): Appended the copied NSData to m_originalData, avoiding an additional copy previously
being made by NSMutableData. Used the new receivedData:decisionHandler: SPI when appropriate.
(WebCore::NetworkExtensionContentFilter::finishedAddingData): Used the new finishedLoadingWithDecisionHandler: SPI when appropriate.
(WebCore::NetworkExtensionContentFilter::needsMoreData): Changed m_neFilterSourceStatus to m_status.
(WebCore::NetworkExtensionContentFilter::didBlockData): Ditto.
(WebCore::NetworkExtensionContentFilter::getReplacementData): Returned the replacement data from NEFilterSource if the load was blocked.
Otherwise, returned the original data.
(WebCore::NetworkExtensionContentFilter::handleDecision): Added a helper to set m_status and m_replacementData, and to signal m_semaphore.
* platform/spi/cocoa/NEFilterSourceSPI.h: Declared the new NEFilterSource SPI on platforms that support it.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@181523 268f45cc-cd09-0410-ab3c-d52691b4dbfc