Enforce canCopyWithMemcpy constraint over TerminatedArray<T>.

third_party/WebKit/Source/wtf/TerminatedArray.h

Index: third_party/WebKit/Source/wtf/TerminatedArray.h
diff --git a/third_party/WebKit/Source/wtf/TerminatedArray.h b/third_party/WebKit/Source/wtf/TerminatedArray.h
index 873bc5b881a6c9e9f1dfcb90b45ff2b2236b4139..18193a4764a80ed26444d047e430fb8d8476dd74 100644
--- a/third_party/WebKit/Source/wtf/TerminatedArray.h
+++ b/third_party/WebKit/Source/wtf/TerminatedArray.h
@@ -6,6 +6,7 @@
 
 #include "wtf/Allocator.h"
 #include "wtf/PtrUtil.h"
+#include "wtf/VectorTraits.h"
 #include "wtf/allocator/Partitions.h"
 #include <memory>
 
@@ -21,6 +22,11 @@ class TerminatedArray {
   WTF_MAKE_NONCOPYABLE(TerminatedArray);
 
  public:
+  // When TerminatedArray::Allocator implementations grow the backing
+  // store, old is copied into the new and larger block.
+  static_assert(VectorTraits<T>::canCopyWithMemcpy,
+                "Array elements must be memory copyable");
+
   T& at(size_t index) { return reinterpret_cast<T*>(this)[index]; }
   const T& at(size_t index) const {
     return reinterpret_cast<const T*>(this)[index];