Added a new mutator called NewInstanceChanger.

Added a new mutator named NewInstanceChanger which changes the type of
the instance to any random type from the pool. Most of the times, it becomes
invalid after being changed. It tries to change the type of invoke direct that
follows. Also, the mutator makes a matching method id if needed.

Test: ran dexfuzz until the mutation showed up.

before:

new-instance v0, LX; // type@0001
invoke-direct {v0}, LX;.<init>:()V // method@0000

after:

new-instance v0, LY; // type@0002
invoke-direct {v0}, LY;.<init>:()V // method@0000

Change-Id: I6eccaebf9910c177e9cff0b5d3ac058565c4331e
diff --git a/tools/dexfuzz/README b/tools/dexfuzz/README
index 1f74262..fff5473 100644
--- a/tools/dexfuzz/README
+++ b/tools/dexfuzz/README
@@ -139,6 +139,7 @@
 InstructionSwapper 80
 InvokeChanger 30
 NewArrayLengthChanger 50
+NewInstanceChanger 10
 NewMethodCaller 10
 NonsenseStringPrinter 10
 OppositeBranchChanger 40