Introduce a RandonNumberGenerator class. Refactor the random/private_random uses in Isolate/Context.

test/cctest/test-assembler-x64.cc

Index: test/cctest/test-assembler-x64.cc
diff --git a/test/cctest/test-assembler-x64.cc b/test/cctest/test-assembler-x64.cc
index d5aaf4f21240fbebbaf483ae6224b62560f39897..f7d2311192303b20c8d38c771e592056add110e5 100644
--- a/test/cctest/test-assembler-x64.cc
+++ b/test/cctest/test-assembler-x64.cc
@@ -90,7 +90,6 @@ static const v8::internal::Register arg2 = rsi;
 
 
 TEST(AssemblerX64ReturnOperation) {
-  OS::SetUp();
   // Allocate an executable page of memory.
   size_t actual_size;
   byte* buffer = static_cast<byte*>(OS::Allocate(Assembler::kMinimalBufferSize,
@@ -113,7 +112,6 @@ TEST(AssemblerX64ReturnOperation) {
 
 
 TEST(AssemblerX64StackOperations) {
-  OS::SetUp();
   // Allocate an executable page of memory.
   size_t actual_size;
   byte* buffer = static_cast<byte*>(OS::Allocate(Assembler::kMinimalBufferSize,
@@ -146,7 +144,6 @@ TEST(AssemblerX64StackOperations) {
 
 
 TEST(AssemblerX64ArithmeticOperations) {
-  OS::SetUp();
   // Allocate an executable page of memory.
   size_t actual_size;
   byte* buffer = static_cast<byte*>(OS::Allocate(Assembler::kMinimalBufferSize,
@@ -169,7 +166,6 @@ TEST(AssemblerX64ArithmeticOperations) {
 
 
 TEST(AssemblerX64ImulOperation) {
-  OS::SetUp();
   // Allocate an executable page of memory.
   size_t actual_size;
   byte* buffer = static_cast<byte*>(OS::Allocate(Assembler::kMinimalBufferSize,
@@ -198,7 +194,6 @@ TEST(AssemblerX64ImulOperation) {
 
 
 TEST(AssemblerX64MemoryOperands) {
-  OS::SetUp();
   // Allocate an executable page of memory.
   size_t actual_size;
   byte* buffer = static_cast<byte*>(OS::Allocate(Assembler::kMinimalBufferSize,
@@ -233,7 +228,6 @@ TEST(AssemblerX64MemoryOperands) {
 
 
 TEST(AssemblerX64ControlFlow) {
-  OS::SetUp();
   // Allocate an executable page of memory.
   size_t actual_size;
   byte* buffer = static_cast<byte*>(OS::Allocate(Assembler::kMinimalBufferSize,
@@ -263,7 +257,6 @@ TEST(AssemblerX64ControlFlow) {
 
 
 TEST(AssemblerX64LoopImmediates) {
-  OS::SetUp();
   // Allocate an executable page of memory.
   size_t actual_size;
   byte* buffer = static_cast<byte*>(OS::Allocate(Assembler::kMinimalBufferSize,