[interpreter] Add support for scalable operands.

test/unittests/interpreter/constant-array-builder-unittest.cc

Index: test/unittests/interpreter/constant-array-builder-unittest.cc
diff --git a/test/unittests/interpreter/constant-array-builder-unittest.cc b/test/unittests/interpreter/constant-array-builder-unittest.cc
index 37de005d4ecf0f11bf437cac4499448ea45a5222..dba3be05ec7c75d03abd33631d28c26020d0b42a 100644
--- a/test/unittests/interpreter/constant-array-builder-unittest.cc
+++ b/test/unittests/interpreter/constant-array-builder-unittest.cc
@@ -109,8 +109,7 @@ TEST_F(ConstantArrayBuilderTest, AllocateEntriesWithIdx8Reservations) {
   }
 }
 
-
-TEST_F(ConstantArrayBuilderTest, AllocateEntriesWithIdx16Reservations) {
+TEST_F(ConstantArrayBuilderTest, AllocateEntriesWithWideReservations) {
   for (size_t reserved = 1; reserved < k8BitCapacity; reserved *= 3) {
     ConstantArrayBuilder builder(isolate(), zone());
     for (size_t i = 0; i < k8BitCapacity; i++) {
@@ -161,6 +160,20 @@ TEST_F(ConstantArrayBuilderTest, ToFixedArray) {
   }
 }
 
+TEST_F(ConstantArrayBuilderTest, ToLargeFixedArray) {

[rmcilroy, 2016/03/17 17:30:50]

How long does this tests take to run? We previously had issues with the 16bit
varient, just want to make sure this doesn't regress test runtime again.

[oth, 2016/03/21 09:16:54]

Good point. I did check but think we'd need to test this either way as there was
a mistake that this catches.

Debug.x64 on MBA 2.13 GHz reports 34-38ms.

+  ConstantArrayBuilder builder(isolate(), zone());
+  static const size_t kNumberOfElements = 37373;
+  for (size_t i = 0; i < kNumberOfElements; i++) {
+    Handle<Object> object = isolate()->factory()->NewNumberFromSize(i);
+    builder.Insert(object);
+    CHECK(builder.At(i)->SameValue(*object));
+  }
+  Handle<FixedArray> constant_array = builder.ToFixedArray();
+  CHECK_EQ(constant_array->length(), kNumberOfElements);
+  for (size_t i = 0; i < kNumberOfElements; i++) {
+    CHECK(constant_array->get(static_cast<int>(i))->SameValue(*builder.At(i)));
+  }
+}
 
 TEST_F(ConstantArrayBuilderTest, GapFilledWhenLowReservationCommitted) {
   ConstantArrayBuilder builder(isolate(), zone());