Bug 1309466 - Enable Array and EnumeratedArray to be brace-initialized with initial contents. r=froydnj

MozReview-Commit-ID: 9sD9Rg4qsy1

--HG--
extra : rebase_source : bef928bca14e6d1a0a207359acfa56ecd93d605b

mfbt/Array.h

@@ -11,6 +11,7 @@
 
 #include "mozilla/Assertions.h"
 #include "mozilla/Attributes.h"
+#include "mozilla/Move.h"
 #include "mozilla/ReverseIterator.h"
 
 #include <stddef.h>
@@ -23,6 +24,16 @@ class Array
   T mArr[Length];
 
 public:
+  Array() {}
+
+  template <typename... Args>
+  MOZ_IMPLICIT Array(Args&&... aArgs)
+    : mArr{mozilla::Forward<Args>(aArgs)...}
+  {
+    static_assert(sizeof...(aArgs) == Length,
+                  "The number of arguments should be equal to the template parameter Length");
+  }
+
   T& operator[](size_t aIndex)
   {
     MOZ_ASSERT(aIndex < Length);

mfbt/EnumeratedArray.h

@@ -54,6 +54,11 @@ private:
 public:
   EnumeratedArray() {}
 
+  template <typename... Args>
+  MOZ_IMPLICIT EnumeratedArray(Args&&... aArgs)
+    : mArray{mozilla::Forward<Args>(aArgs)...}
+  {}
+
   explicit EnumeratedArray(const EnumeratedArray& aOther)
   {
     for (size_t i = 0; i < kSize; i++) {