Fix the bug that cast should not be public.

cast is a templated function and should
not be public.

Test: `mma`
Change-Id: I30193e022c210c78b16fdf3b5f331a0ef3cbbb27
diff --git a/ArrayType.cpp b/ArrayType.cpp
index 9d3f8ff..6b4a01b 100644
--- a/ArrayType.cpp
+++ b/ArrayType.cpp
@@ -36,7 +36,7 @@
 }
 
 void ArrayType::addDimension(ConstantExpression *size) {
-    mSizes.insert(mSizes.begin(), size->cast<size_t>());
+    mSizes.insert(mSizes.begin(), size->castSizeT());
     mSizeComments.insert(mSizeComments.begin(), size->description());
 }