[Cocoa] Add tvOS and watchOS to SUPPORTED_PLATFORMS

[Cocoa] Add tvOS and watchOS to SUPPORTED_PLATFORMS
https://bugs.webkit.org/show_bug.cgi?id=150819

Reviewed by Dan Bernstein.

This tells Xcode to include these platforms in its Devices dropdown, making it possible to build in the IDE.

Source/bmalloc:

* Configurations/Base.xcconfig:

Source/JavaScriptCore:

* Configurations/Base.xcconfig:

Source/ThirdParty:

* gtest/xcode/Config/General.xcconfig:

Source/ThirdParty/ANGLE:

* Configurations/Base.xcconfig:

Source/WebCore:

* Configurations/Base.xcconfig:

Source/WebInspectorUI:

* Configurations/Base.xcconfig:

Source/WebKit/mac:

* Configurations/Base.xcconfig:

Source/WebKit2:

* Configurations/Base.xcconfig:

Source/WTF:

* Configurations/Base.xcconfig:

Tools:

* DumpRenderTree/mac/Configurations/Base.xcconfig:
* MiniBrowser/Configurations/Base.xcconfig:
* TestWebKitAPI/Configurations/Base.xcconfig:
* WebKitTestRunner/Configurations/Base.xcconfig:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@191920 268f45cc-cd09-0410-ab3c-d52691b4dbfc