[turbofan] Don't spread global flag checks all over the compiler code.

src/compiler.h

Index: src/compiler.h
diff --git a/src/compiler.h b/src/compiler.h
index f55c061b5c22ecb499ebb8bd71b1f62c3c773211..8e0aab931ca9bb8fa2ad7e9a3b74c1fcf0c0221d 100644
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -127,7 +127,8 @@ class CompilationInfo {
     kSplittingEnabled = 1 << 13,
     kBuiltinInliningEnabled = 1 << 14,
     kTypeFeedbackEnabled = 1 << 15,
-    kDeoptimizationEnabled = 1 << 16
+    kDeoptimizationEnabled = 1 << 16,
+    kSourcePositionsEnabled = 1 << 17
   };
 
   explicit CompilationInfo(ParseInfo* parse_info);
@@ -224,6 +225,12 @@ class CompilationInfo {
     return GetFlag(kDeoptimizationEnabled);
   }
 
+  void MarkAsSourcePositionsEnabled() { SetFlag(kSourcePositionsEnabled); }
+
+  bool is_source_positions_enabled() const {
+    return GetFlag(kSourcePositionsEnabled);
+  }
+
   void MarkAsInliningEnabled() { SetFlag(kInliningEnabled); }
 
   bool is_inlining_enabled() const { return GetFlag(kInliningEnabled); }