ART: Boolean simplifier

The optimization recognizes the negation pattern generated by 'javac'
and replaces it with a single condition. To this end, boolean values
are now consistently assumed to be represented by an integer.

This is a first optimization which deletes blocks from the HGraph and
does so by replacing the corresponding entries with null. Hence,
existing code can continue indexing the list of blocks with the block
ID, but must check for null when iterating over the list.

Change-Id: I7779da69cfa925c6521938ad0bcc11bc52335583
diff --git a/runtime/primitive.h b/runtime/primitive.h
index 2d6b6b3..d11f1e9 100644
--- a/runtime/primitive.h
+++ b/runtime/primitive.h
@@ -153,7 +153,10 @@
   }
 
   static bool IsIntegralType(Type type) {
+    // Java language does not allow treating boolean as an integral type but our
+    // bit representation makes it safe.
     switch (type) {
+      case kPrimBoolean:
       case kPrimByte:
       case kPrimChar:
       case kPrimShort: