diff --git a/core/connection_db.js b/core/connection_db.js
index f1968f957..476b824bb 100644
--- a/core/connection_db.js
+++ b/core/connection_db.js
@@ -36,15 +36,14 @@ goog.require('Blockly.Connection');
  * @constructor
  */
 Blockly.ConnectionDB = function() {
+  /**
+   * Array of connections sorted by y coordinate.
+   * @type {!Array.<!Blockly.Connection>}
+   * @private
+   */
+  this.connections_ = [];
 };
 
-Blockly.ConnectionDB.prototype = new Array();
-/**
- * Don't inherit the constructor from Array.
- * @type {!Function}
- */
-Blockly.ConnectionDB.constructor = Blockly.ConnectionDB;
-
 /**
  * Add a connection to the database.  Must not already exist in DB.
  * @param {!Blockly.Connection} connection The connection to be added.
@@ -58,7 +57,7 @@ Blockly.ConnectionDB.prototype.addConnection = function(connection) {
     return;
   }
   var position = this.findPositionForConnection_(connection);
-  this.splice(position, 0, connection);
+  this.connections_.splice(position, 0, connection);
   connection.inDB_ = true;
 };
 
@@ -71,12 +70,12 @@ Blockly.ConnectionDB.prototype.addConnection = function(connection) {
  *     not found.
  */
 Blockly.ConnectionDB.prototype.findConnection = function(conn) {
-  if (!this.length) {
+  if (!this.connections_.length) {
     return -1;
   }
 
   var bestGuess = this.findPositionForConnection_(conn);
-  if (bestGuess >= this.length) {
+  if (bestGuess >= this.connections_.length) {
     // Not in list
     return -1;
   }
@@ -85,15 +84,16 @@ Blockly.ConnectionDB.prototype.findConnection = function(conn) {
   // Walk forward and back on the y axis looking for the connection.
   var pointerMin = bestGuess;
   var pointerMax = bestGuess;
-  while (pointerMin >= 0 && this[pointerMin].y_ == yPos) {
-    if (this[pointerMin] == conn) {
+  while (pointerMin >= 0 && this.connections_[pointerMin].y_ == yPos) {
+    if (this.connections_[pointerMin] == conn) {
       return pointerMin;
     }
     pointerMin--;
   }
 
-  while (pointerMax < this.length && this[pointerMax].y_ == yPos) {
-    if (this[pointerMax] == conn) {
+  while (pointerMax < this.connections_.length &&
+         this.connections_[pointerMax].y_ == yPos) {
+    if (this.connections_[pointerMax] == conn) {
       return pointerMax;
     }
     pointerMax++;
@@ -111,16 +111,16 @@ Blockly.ConnectionDB.prototype.findConnection = function(conn) {
  */
 Blockly.ConnectionDB.prototype.findPositionForConnection_ = function(
     connection) {
-  if (!this.length) {
+  if (!this.connections_.length) {
     return 0;
   }
   var pointerMin = 0;
-  var pointerMax = this.length;
+  var pointerMax = this.connections_.length;
   while (pointerMin < pointerMax) {
     var pointerMid = Math.floor((pointerMin + pointerMax) / 2);
-    if (this[pointerMid].y_ < connection.y_) {
+    if (this.connections_[pointerMid].y_ < connection.y_) {
       pointerMin = pointerMid + 1;
-    } else if (this[pointerMid].y_ > connection.y_) {
+    } else if (this.connections_[pointerMid].y_ > connection.y_) {
       pointerMax = pointerMid;
     } else {
       pointerMin = pointerMid;
@@ -144,7 +144,7 @@ Blockly.ConnectionDB.prototype.removeConnection_ = function(connection) {
     throw Error('Unable to find connection in connectionDB.');
   }
   connection.inDB_ = false;
-  this.splice(removalIndex, 1);
+  this.connections_.splice(removalIndex, 1);
 };
 
 /**
@@ -156,7 +156,7 @@ Blockly.ConnectionDB.prototype.removeConnection_ = function(connection) {
  * @return {!Array.<Blockly.Connection>} List of connections.
  */
 Blockly.ConnectionDB.prototype.getNeighbours = function(connection, maxRadius) {
-  var db = this;
+  var db = this.connections_;
   var currentX = connection.x_;
   var currentY = connection.y_;
 
@@ -218,7 +218,7 @@ Blockly.ConnectionDB.prototype.getNeighbours = function(connection, maxRadius) {
  * @private
  */
 Blockly.ConnectionDB.prototype.isInYRange_ = function(index, baseY, maxRadius) {
-  return (Math.abs(this[index].y_ - baseY) <= maxRadius);
+  return (Math.abs(this.connections_[index].y_ - baseY) <= maxRadius);
 };
 
 /**
@@ -235,7 +235,7 @@ Blockly.ConnectionDB.prototype.isInYRange_ = function(index, baseY, maxRadius) {
 Blockly.ConnectionDB.prototype.searchForClosest = function(conn, maxRadius,
     dxy) {
   // Don't bother.
-  if (!this.length) {
+  if (!this.connections_.length) {
     return {connection: null, radius: maxRadius};
   }
 
@@ -258,7 +258,7 @@ Blockly.ConnectionDB.prototype.searchForClosest = function(conn, maxRadius,
   // Walk forward and back on the y axis looking for the closest x,y point.
   var pointerMin = closestIndex - 1;
   while (pointerMin >= 0 && this.isInYRange_(pointerMin, conn.y_, maxRadius)) {
-    temp = this[pointerMin];
+    temp = this.connections_[pointerMin];
     if (conn.isConnectionAllowed(temp, bestRadius)) {
       bestConnection = temp;
       bestRadius = temp.distanceFrom(conn);
@@ -267,9 +267,9 @@ Blockly.ConnectionDB.prototype.searchForClosest = function(conn, maxRadius,
   }
 
   var pointerMax = closestIndex;
-  while (pointerMax < this.length && this.isInYRange_(pointerMax, conn.y_,
-      maxRadius)) {
-    temp = this[pointerMax];
+  while (pointerMax < this.connections_.length &&
+      this.isInYRange_(pointerMax, conn.y_, maxRadius)) {
+    temp = this.connections_[pointerMax];
     if (conn.isConnectionAllowed(temp, bestRadius)) {
       bestConnection = temp;
       bestRadius = temp.distanceFrom(conn);
diff --git a/tests/jsunit/connection_db_test.js b/tests/jsunit/connection_db_test.js
index f488d5a96..b7e087558 100644
--- a/tests/jsunit/connection_db_test.js
+++ b/tests/jsunit/connection_db_test.js
@@ -20,10 +20,10 @@
 'use strict';
 
 function verify_DB_(msg, expected, db) {
-   var equal = (expected.length == db.length);
+   var equal = (expected.length == db.connections_.length);
    if (equal) {
      for (var i = 0; i < expected.length; i++) {
-       if (expected[i] != db[i]) {
+       if (expected[i] != db.connections_[i]) {
          equal = false;
          break;
        }
@@ -32,7 +32,7 @@ function verify_DB_(msg, expected, db) {
    if (equal) {
      assertTrue(msg, true);
    } else {
-     assertEquals(msg, expected, db);
+     assertEquals(msg, expected, db.connections_);
    }
 }
 
@@ -122,21 +122,21 @@ function test_DB_getNeighbours() {
   var result = helper_getNeighbours(db, 0, 0, 4);
   assertEquals(5, result.length);
   for (i = 0; i < result.length; i++) {
-    assertNotEquals(result.indexOf(db[i]), -1); // contains
+    assertNotEquals(result.indexOf(db.connections_[i]), -1); // contains
   }
 
   // Test block belongs at middle.
   result = helper_getNeighbours(db, 0, 4, 2);
   assertEquals(5, result.length);
   for (i = 0; i < result.length; i++) {
-    assertNotEquals(result.indexOf(db[i + 2]), -1); // contains
+    assertNotEquals(result.indexOf(db.connections_[i + 2]), -1); // contains
   }
 
   // Test block belongs at end.
   result = helper_getNeighbours(db, 0, 9, 4);
   assertEquals(5, result.length);
   for (i = 0; i < result.length; i++) {
-    assertNotEquals(result.indexOf(db[i + 5]), -1); // contains
+    assertNotEquals(result.indexOf(db.connections_[i + 5]), -1); // contains
   }
 
   // Test block has no neighbours due to being out of range in the x direction.
@@ -165,7 +165,7 @@ function test_DB_findPositionForConnection() {
   db.addConnection(helper_createConnection(0, 5, Blockly.PREVIOUS_STATEMENT,
       null, true));
 
-  assertEquals(5, db.length);
+  assertEquals(5, db.connections_.length);
   var conn = helper_createConnection(0, 3, Blockly.PREVIOUS_STATEMENT, null,
       true);
   assertEquals(3, db.findPositionForConnection_(conn));
@@ -183,7 +183,7 @@ function test_DB_findConnection() {
   var conn = helper_createConnection(3, 3, Blockly.PREVIOUS_STATEMENT, null,
       true);
   db.addConnection(conn);
-  assertEquals(conn, db[db.findConnection(conn)]);
+  assertEquals(conn, db.connections_[db.findConnection(conn)]);
 
   conn = helper_createConnection(3, 3, Blockly.PREVIOUS_STATEMENT, null, true);
   assertEquals(-1, db.findConnection(conn));
@@ -197,7 +197,7 @@ function test_DB_ordering() {
   }
 
   for (i = 0; i < 10; i++) {
-      assertEquals(i, db[i].y_);
+      assertEquals(i, db.connections_[i].y_);
   }
 
   // quasi-random
@@ -221,7 +221,7 @@ function test_DB_ordering() {
   }
 
   for (i = 1; i < xCoords.length; i++) {
-    assertTrue(db[i].y_ >= db[i - 1].y_);
+    assertTrue(db.connections_[i].y_ >= db.connections_[i - 1].y_);
   }
 }
 
@@ -246,13 +246,13 @@ function test_SearchForClosest() {
   }
 
   // Should be at 0, 9.
-  var last = db[db.length - 1];
+  var last = db.connections_[db.connections_.length - 1];
   // Correct connection is last in db; many connections in radius.
   assertEquals(last, helper_searchDB(db, 0, 10, 15, sharedWorkspace));
   // Nothing nearby.
   assertEquals(null, helper_searchDB(db, 100, 100, 3, sharedWorkspace));
   // First in db, exact match.
-  assertEquals(db[0], helper_searchDB(db, 0, 0, 0, sharedWorkspace));
+  assertEquals(db.connections_[0], helper_searchDB(db, 0, 0, 0, sharedWorkspace));
 
   tempConn = helper_createConnection(6, 6, Blockly.PREVIOUS_STATEMENT,
       sharedWorkspace, true);