Move TextStream to Source/platform/text/

Source/platform/blink_platform.gypi

 {
   'variables': {
     'platform_files': [
       'clipboard/ClipboardMimeTypes.cpp',
       'clipboard/ClipboardMimeTypes.h',
       'clipboard/ClipboardUtilitiesPosix.cpp',
       'clipboard/ClipboardUtilitiesWin.cpp',
       'clipboard/ClipboardUtilities.cpp',
       'clipboard/ClipboardUtilities.h',
       'exported/Platform.cpp',
@@ skipping 30 matching lines @@
       'network/SocketStreamHandle.cpp',
       'network/SocketStreamHandle.h',
       'network/SocketStreamHandleClient.h',
       'network/SocketStreamHandleInternal.h',
       'transforms/AffineTransform.cpp',
       'transforms/AffineTransform.h',
       'transforms/TransformationMatrix.cpp',
       'transforms/TransformationMatrix.h',
       'text/BidiContext.cpp',
       'text/BidiContext.h',
+      'text/TextStream.cpp',
+      'text/TextStream.h',
       'Clock.cpp',
       'Clock.h',
       'DateComponents.cpp',
       'DateComponents.h',
       'Decimal.cpp',
       'Decimal.h',
       'EventTracer.cpp',
       'EventTracer.h',
       'FileChooser.cpp',
       'FileChooser.h',
@@ skipping 30 matching lines @@
     'platform_test_files': [
       'clipboard/ClipboardUtilitiesTest.cpp',
       'text/DateTimeFormatTest.cpp',
       'ClockTest.cpp',
       'DecimalTest.cpp',
       'LayoutUnitTest.cpp',
       'SharedBufferTest.cpp',
     ],
   },
 }