Store TFunction::returnType by a const pointer.

On 32-bit Android this change saves ~30KiB per compiler instance.

BUG=492725

Change-Id: I8bea48d57ee7eac0a0ee417035085c0d335aea09
Reviewed-on: https://chromium-review.googlesource.com/281047
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Dmitry Skiba <dskiba@google.com>
diff --git a/src/compiler/translator/ParseContext.cpp b/src/compiler/translator/ParseContext.cpp
index 2d08172..6f4bba4 100644
--- a/src/compiler/translator/ParseContext.cpp
+++ b/src/compiler/translator/ParseContext.cpp
@@ -1877,7 +1877,7 @@
     }
 
     TString tempString;
-    TType type(publicType);
+    const TType *type = new TType(publicType);
     return new TFunction(&tempString, type, op);
 }