Minimal implementation and tests of observable array methods

src/array.js

Index: src/array.js
diff --git a/src/array.js b/src/array.js
index 155d5659415c6eb5bccc84e221f477100da448ee..37053ce67e5fe8762d580f303c880acd3db513b0 100644
--- a/src/array.js
+++ b/src/array.js
@@ -441,8 +441,8 @@ function ArrayPop() {
   }
   n--;
   var value = this[n];
-  this.length = n;
   delete this[n];

[adamk, 2012/11/09 12:06:30]

This change is required for proper operation, and is the proper ordering per the
spec:

http://ecma-international.org/ecma-262/5.1/#sec-15.4.4.6

+  this.length = n;
   return value;
 }
 
@@ -581,7 +581,7 @@ function ArrayShift() {
 
   var first = this[0];
 
-  if (IS_ARRAY(this)) {
+  if (IS_ARRAY(this) && !%IsObserved(this)) {
     SmartMove(this, 0, 1, len, 0);
   } else {
     SimpleMove(this, 0, 1, len, 0);
@@ -602,7 +602,7 @@ function ArrayUnshift(arg1) {  // length == 1
   var len = TO_UINT32(this.length);
   var num_arguments = %_ArgumentsLength();
 
-  if (IS_ARRAY(this)) {
+  if (IS_ARRAY(this) && !%IsObserved(this)) {
     SmartMove(this, 0, 0, len, num_arguments);
   } else {
     SimpleMove(this, 0, 0, len, num_arguments);
@@ -649,6 +649,7 @@ function ArraySlice(start, end) {
   if (end_i < start_i) return result;
 
   if (IS_ARRAY(this) &&
+      !%IsObserved(this) &&
       (end_i > 1000) &&
       (%EstimateNumberOfElements(this) < end_i)) {
     SmartSlice(this, start_i, end_i - start_i, len, result);
@@ -705,7 +706,9 @@ function ArraySplice(start, delete_count) {
 
   var use_simple_splice = true;
 
-  if (IS_ARRAY(this) && num_additional_args !== del_count) {
+  if (IS_ARRAY(this) &&
+      !%IsObserved(this) &&
+      num_additional_args !== del_count) {
     // If we are only deleting/moving a few things near the end of the
     // array then the simple version is going to be faster, because it
     // doesn't touch most of the array.