--- a/nashorn/src/jdk/nashorn/internal/objects/Global.java	Thu Oct 17 17:33:16 2013 +0200
+++ b/nashorn/src/jdk/nashorn/internal/objects/Global.java	Fri Oct 18 12:50:21 2013 +0200
@@ -1665,9 +1665,9 @@
         final ScriptObject stringPrototype = getStringPrototype();
         stringPrototype.addOwnProperty("length", Attribute.NON_ENUMERABLE_CONSTANT, 0.0);
 
-        // add Array.prototype.length
+        // set isArray flag on Array.prototype
         final ScriptObject arrayPrototype = getArrayPrototype();
-        arrayPrototype.addOwnProperty("length", Attribute.NOT_ENUMERABLE|Attribute.NOT_CONFIGURABLE, 0.0);
+        arrayPrototype.setIsArray();
 
         this.DEFAULT_DATE = new NativeDate(Double.NaN, this);
 

--- a/nashorn/src/jdk/nashorn/internal/objects/NativeArray.java	Thu Oct 17 17:33:16 2013 +0200
+++ b/nashorn/src/jdk/nashorn/internal/objects/NativeArray.java	Fri Oct 18 12:50:21 2013 +0200
@@ -372,9 +372,7 @@
      */
     @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)
     public static Object isArray(final Object self, final Object arg) {
-        return isArray(arg) || (arg == Global.instance().getArrayPrototype())
-                || (arg instanceof NativeRegExpExecResult)
-                || (arg instanceof JSObject && ((JSObject)arg).isArray());
+        return isArray(arg) || (arg instanceof JSObject && ((JSObject)arg).isArray());
     }
 
     /**
@@ -403,6 +401,26 @@
         }
     }
 
+    /**
+     * Prototype length getter
+     * @param self self reference
+     * @return the length of the object
+     */
+    @Getter(name = "length", where = Where.PROTOTYPE, attributes = Attribute.NOT_ENUMERABLE | Attribute.NOT_CONFIGURABLE)
+    public static Object getProtoLength(final Object self) {
+        return length(self);  // Same as instance getter but we can't make nasgen use the same method for prototype
+    }
+
+    /**
+     * Prototype length setter
+     * @param self   self reference
+     * @param length new length property
+     */
+    @Setter(name = "length", where = Where.PROTOTYPE, attributes = Attribute.NOT_ENUMERABLE | Attribute.NOT_CONFIGURABLE)
+    public static void setProtoLength(final Object self, final Object length) {
+        length(self, length);  // Same as instance setter but we can't make nasgen use the same method for prototype
+    }
+
     static long validLength(final Object length, final boolean reject) {
         final double doubleLength = JSType.toNumber(length);
         if (!Double.isNaN(doubleLength) && JSType.isRepresentableAsLong(doubleLength)) {

--- a/nashorn/src/jdk/nashorn/internal/objects/NativeJSAdapter.java	Thu Oct 17 17:33:16 2013 +0200
+++ b/nashorn/src/jdk/nashorn/internal/objects/NativeJSAdapter.java	Fri Oct 18 12:50:21 2013 +0200
@@ -629,7 +629,8 @@
                     // to name. Probably not a big deal, but if we can ever make it leaner, it'd be nice.
                     return new GuardedInvocation(MH.dropArguments(MH.constant(Object.class,
                             func.makeBoundFunction(this, new Object[] { name })), 0, Object.class),
-                            adaptee.getMap().getProtoGetSwitchPoint(adaptee.getProto(), __call__), testJSAdaptor(adaptee, null, null, null));
+                            adaptee.getMap().getProtoGetSwitchPoint(adaptee.getProto(), __call__),
+                            testJSAdaptor(adaptee, null, null, null));
                 }
             }
             throw typeError("no.such.function", desc.getNameToken(2), ScriptRuntime.safeToString(this));

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nashorn/test/script/basic/JDK-8026805.js	Fri Oct 18 12:50:21 2013 +0200
@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ * 
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ * 
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ * 
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ * 
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * JDK-8026805: Array.prototype.length doesn't work as expected
+ *
+ * @test
+ * @run
+ */
+
+if (Array.prototype.length !== 0) {
+    throw new Error("Initial length not 0");
+}
+
+Array.prototype[3] = 1;
+
+if (Array.prototype.length !== 4) {
+    throw new Error("length not updated to 4");
+}
+
+Array.prototype.length = 0;
+
+if (Array.prototype.length !== 0) {
+    throw new Error("length not reset to 0");
+}
+
+if (3 in Array.prototype) {
+    throw new Error("array element not deleted");
+}