[debug] always add debug slot for statements.

src/assembler.h

Index: src/assembler.h
diff --git a/src/assembler.h b/src/assembler.h
index 2ae221e355fba5ecedb2b472fb116930819deab5..35bc0afdb0d4f2ee4dd194c1fff460fe2c10e35c 100644
--- a/src/assembler.h
+++ b/src/assembler.h
@@ -1152,14 +1152,14 @@ class AssemblerPositionsRecorder : public PositionsRecorder {
         written_statement_position_(RelocInfo::kNoPosition) {}
 
   // Set current position to pos.
-  bool RecordPosition(int pos);
+  void RecordPosition(int pos);
 
   // Set current statement position to pos.
-  bool RecordStatementPosition(int pos);
+  void RecordStatementPosition(int pos);
 
  private:
   // Write recorded positions to relocation information.
-  bool WriteRecordedPositions();
+  void WriteRecordedPositions();
 
   Assembler* assembler_;