Move files in wtf/ to platform/wtf/ (Part 4).

third_party/WebKit/Source/platform/wtf/BUILD.gn

Index: third_party/WebKit/Source/platform/wtf/BUILD.gn
diff --git a/third_party/WebKit/Source/platform/wtf/BUILD.gn b/third_party/WebKit/Source/platform/wtf/BUILD.gn
index 01bc21008c324112724bc21b00e83b21d6f339b7..e1c222dd36bb6292c50cfa5c97809c235a5bbae3 100644
--- a/third_party/WebKit/Source/platform/wtf/BUILD.gn
+++ b/third_party/WebKit/Source/platform/wtf/BUILD.gn
@@ -59,8 +59,12 @@ config("wtf_config") {
 
 source_set("platform_wtf") {
   sources = [
+    "ASCIICType.cpp",
+    "ASCIICType.h",
     "AddressSanitizer.h",
     "Alignment.h",
+    "Assertions.h",
+    "Atomics.h",
     "AutoReset.h",
     "BitwiseOperations.h",
     "ByteSwap.h",
@@ -83,12 +87,16 @@ source_set("platform_wtf") {
     "NotFound.h",
     "Optional.h",
     "SizeAssertions.h",
+    "SpinLock.h",
     "StaticConstructors.h",
+    "StringExtras.h",
     "Time.h",
     "TriState.h",
     "TypeTraits.h",
     "WTFExport.h",
     "build_config.h",
+    "text/Unicode.h",
+    "text/icu/UnicodeIcu.h",
   ]
 
   configs += [