Fixes:

../../test/cctest/compiler/test-js-typed-lowering.cc:224:14:
 error: ‘kJSTypes’ defined but not used [-Werror=unused-variable]
  static Type* kJSTypes[] = {Type::Undefined(), Type::Null(),   Type::Boolean(),

../../src/bignum.cc: In member function
 ‘void v8::internal::Bignum::AssignDecimalString(Vector<const char>)’:
  ../../src/bignum.cc:80:6: error: assuming signed overflow does not occur when
  assuming that (X + c) < X is always false [-Werror=strict-overflow]

../../src/compiler/ia32/code-generator-ia32.cc:1366:3:
  required from here ../../src/base/logging.h:123:26:
   error: comparison between signed and unsigned integer expressions
   [-Werror=sign-compare] DEFINE_CHECK_OP_IMPL(EQ, ==)

BUG=

Review URL: https://codereview.chromium.org/1371823002

Cr-Commit-Position: refs/heads/master@{#31095}