Make 'hidden' the default visibility for gcc. Add build option,

test/cctest/test-conversions.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 
 #include <stdlib.h>
 
 #include "v8.h"
 
 #include "platform.h"
 #include "cctest.h"
 
 using namespace v8::internal;
@@ skipping 73 matching lines @@
 
 
 TEST(NonStrDecimalLiteral) {
   CHECK(isnan(StringToDouble(" ", NO_FLAGS, OS::nan_value())));
   CHECK(isnan(StringToDouble("", NO_FLAGS, OS::nan_value())));
   CHECK(isnan(StringToDouble(" ", NO_FLAGS, OS::nan_value())));
   CHECK_EQ(0.0, StringToDouble("", NO_FLAGS));
   CHECK_EQ(0.0, StringToDouble(" ", NO_FLAGS));
 }
 
+class OneBit1: public BitField<uint32_t, 0, 1> {};
+class OneBit2: public BitField<uint32_t, 7, 1> {};
+class EightBit1: public BitField<uint32_t, 0, 8> {};
+class EightBit2: public BitField<uint32_t, 13, 8> {};
 
 TEST(BitField) {
   uint32_t x;
 
   // One bit bit field can hold values 0 and 1.
-  class OneBit1: public BitField<uint32_t, 0, 1> {};
-  class OneBit2: public BitField<uint32_t, 7, 1> {};
   CHECK(!OneBit1::is_valid(static_cast<uint32_t>(-1)));
   CHECK(!OneBit2::is_valid(static_cast<uint32_t>(-1)));
   for (int i = 0; i < 2; i++) {
     CHECK(OneBit1::is_valid(i));
     x = OneBit1::encode(i);
     CHECK_EQ(i, OneBit1::decode(x));
 
     CHECK(OneBit2::is_valid(i));
     x = OneBit2::encode(i);
     CHECK_EQ(i, OneBit2::decode(x));
   }
   CHECK(!OneBit1::is_valid(2));
   CHECK(!OneBit2::is_valid(2));
 
   // Eight bit bit field can hold values from 0 tp 255.
-  class EightBit1: public BitField<uint32_t, 0, 8> {};
-  class EightBit2: public BitField<uint32_t, 13, 8> {};
   CHECK(!EightBit1::is_valid(static_cast<uint32_t>(-1)));
   CHECK(!EightBit2::is_valid(static_cast<uint32_t>(-1)));
   for (int i = 0; i < 256; i++) {
     CHECK(EightBit1::is_valid(i));
     x = EightBit1::encode(i);
     CHECK_EQ(i, EightBit1::decode(x));
     CHECK(EightBit2::is_valid(i));
     x = EightBit2::encode(i);
     CHECK_EQ(i, EightBit2::decode(x));
   }
   CHECK(!EightBit1::is_valid(256));
   CHECK(!EightBit2::is_valid(256));
 }