[turbofan] Add DebugBreak machine operator and support

src/code-stub-assembler.h

Index: src/code-stub-assembler.h
diff --git a/src/code-stub-assembler.h b/src/code-stub-assembler.h
index 19b798216f6fe881be4d032cb77e6a55fceb006d..c24d3785d84540fcb96cb40a8f4fda6cceabab35 100644
--- a/src/code-stub-assembler.h
+++ b/src/code-stub-assembler.h
@@ -75,6 +75,8 @@ class CodeStubAssembler : public compiler::CodeAssembler {
   compiler::Node* InnerAllocate(compiler::Node* previous,
                                 compiler::Node* offset);
 
+  void Assert(compiler::Node* condition);
+
   // Check a value for smi-ness
   compiler::Node* WordIsSmi(compiler::Node* a);
   // Check that the value is a positive smi.