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/SymbolTable.cpp b/src/compiler/translator/SymbolTable.cpp
index cc6879e..35887d0 100644
--- a/src/compiler/translator/SymbolTable.cpp
+++ b/src/compiler/translator/SymbolTable.cpp
@@ -229,7 +229,7 @@
     }
     else
     {
-        TFunction *function = new TFunction(NewPoolTString(name), *rvalue, op, ext);
+        TFunction *function = new TFunction(NewPoolTString(name), rvalue, op, ext);
 
         function->addParameter(TConstParameter(ptype1));