Remove unused function

This is now used only internally in libaxolotl, which provides its own
definition.

// FREEBIE

js/libtextsecure.js

@@ -36024,18 +36024,6 @@ function getStringable(thing) {
                 thing.__proto__ == StaticByteBufferProto)));
 }
 
-function isEqual(a, b, mayBeShort) {
-    // TODO: Special-case arraybuffers, etc
-    if (a === undefined || b === undefined)
-        return false;
-    a = getString(a);
-    b = getString(b);
-    var maxLength = mayBeShort ? Math.min(a.length, b.length) : Math.max(a.length, b.length);
-    if (maxLength < 5)
-        throw new Error("a/b compare too short");
-    return a.substring(0, Math.min(maxLength, a.length)) == b.substring(0, Math.min(maxLength, b.length));
-}
-
 function toArrayBuffer(thing) {
     //TODO: Optimize this for specific cases
     if (thing === undefined)

libtextsecure/helpers.js

@@ -33,18 +33,6 @@ function getStringable(thing) {
                 thing.__proto__ == StaticByteBufferProto)));
 }
 
-function isEqual(a, b, mayBeShort) {
-    // TODO: Special-case arraybuffers, etc
-    if (a === undefined || b === undefined)
-        return false;
-    a = getString(a);
-    b = getString(b);
-    var maxLength = mayBeShort ? Math.min(a.length, b.length) : Math.max(a.length, b.length);
-    if (maxLength < 5)
-        throw new Error("a/b compare too short");
-    return a.substring(0, Math.min(maxLength, a.length)) == b.substring(0, Math.min(maxLength, b.length));
-}
-
 function toArrayBuffer(thing) {
     //TODO: Optimize this for specific cases
     if (thing === undefined)

libtextsecure/test/helpers_test.js

@@ -32,27 +32,4 @@ describe("Helpers", function() {
                        Error, /Tried to convert a non-stringable thing/);
       });
   });
-
-  describe("isEqual", function(){
-      it('returns false when a or b is undefined', function(){
-          assert.isFalse(isEqual("defined value", undefined, false));
-          assert.isFalse(isEqual(undefined, "defined value", false));
-      });
-      it('returns true when a and b are equal', function(){
-          var a = "same value";
-          var b = "same value";
-          assert.isTrue(isEqual(a, b, false));
-      });
-      it('returns false when a and b are not equal', function(){
-          var a = "same value";
-          var b = "diferent value";
-          assert.isFalse(isEqual(a, b, false));
-      });
-      it('throws an error when a/b compare is too short', function(){
-          var a = "1234";
-          var b = "1234";
-          assert.throw(function() { isEqual(a, b, true) },
-                       Error, /a\/b compare too short/);
-      });
-  });
 });