Move all static constants in dtoa/cached-powers.* to .rodata section

Source/wtf/ThreadingPthreads.cpp

Index: Source/wtf/ThreadingPthreads.cpp
diff --git a/Source/wtf/ThreadingPthreads.cpp b/Source/wtf/ThreadingPthreads.cpp
index 8f5df6487be5c7d372553c9585361f797ef94839..1fbe99eae95827ab311de156aff2d380c5a1a888 100644
--- a/Source/wtf/ThreadingPthreads.cpp
+++ b/Source/wtf/ThreadingPthreads.cpp
@@ -114,7 +114,6 @@ void initializeThreading()
     // This should only be called once.
     ASSERT(!atomicallyInitializedStaticMutex);
 
-    WTF::double_conversion::initialize();
     // StringImpl::empty() does not construct its static string in a threadsafe fashion,
     // so ensure it has been initialized from here.
     StringImpl::empty();