typed arrays: fix DataView endianness regression

Fix an off-by-one error introduced in 9fe3734 that caused a regression
in the default endianness used for writes in DataView::setGeneric().

Fixes #4626.

src/v8_typed_array.cc

@@ -714,7 +714,7 @@ class DataView {
     // NOTE(deanm): args[1]->BooleanValue when the argument was not passed in
     // gives us the right answer, but seems to be very slow.  This seems to be
     // the cost of calling BooleanValue() on undefined.
-    bool little_endian = args.Length() > 1 ? args[1]->BooleanValue() : false;
+    bool little_endian = args.Length() > 2 ? args[2]->BooleanValue() : false;
     // TODO(deanm): All of these things should be cacheable.
     int element_size = v8_typed_array::SizeOfArrayElementForType(
         args.This()->GetIndexedPropertiesExternalArrayDataType());

test/simple/test-typed-arrays.js

@@ -192,3 +192,12 @@ assert.throws(function() {
   var buf = new DataView(new ArrayBuffer(8));
   buf.setFloat64(0xffffffff, 0.0, true);
 }, /Index out of range/);
+
+// DataView::setGeneric() default endianness regression test,
+// see https://github.com/joyent/node/issues/4626
+(function() {
+  var buf = new Uint8Array(2);
+  var view = new DataView(buf);
+  view.setUint16(0, 1);
+  assert.equal(view.getUint16(0), 1);
+})();