Add EXPORT specifier in /third_party/blink/renderer/platform/wtf

To speed up build time on windows component build, I will enable newly added /Zc:dllexportInlines- flag. The flag is similar to -fvisibility-inlines-hidden in gcc/clang.

This flag makes inline member function is not exported if it does not have static local variables. But in few classes of chromium, we need to add additional EXPORT specifier to prevent link failure.

This is a part of effort adding EXPORT speicifer to enable the flag.

Master CL is
https://chromium-review.googlesource.com/c/chromium/src/+/1317069

This CL was uploaded by git cl split.

R=erik.corry@gmail.com

Bug: 901709
Change-Id: I942c126cf68df4b242c7e49f05c2d7696e9d1b9e
Reviewed-on: https://chromium-review.googlesource.com/c/1322175
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606090}

third_party/blink/renderer/platform/wtf/typed_arrays/array_buffer_contents.h

@@ -160,7 +160,7 @@ class WTF_EXPORT ArrayBufferContents {
   static void DefaultAdjustAmountOfExternalAllocatedMemoryFunction(
       int64_t diff);
 
-  class DataHolder : public ThreadSafeRefCounted<DataHolder> {
+  class WTF_EXPORT DataHolder : public ThreadSafeRefCounted<DataHolder> {
     DISALLOW_COPY_AND_ASSIGN(DataHolder);
 
    public: