[interpreter] Introduce bytecode generation pipeline.

src/interpreter/source-position-table.h

Index: src/interpreter/source-position-table.h
diff --git a/src/interpreter/source-position-table.h b/src/interpreter/source-position-table.h
index 3ac58d621787939383f8d442f241138e06df05a5..2041dd1db727afcf826e31d4313b2b7dd12389d2 100644
--- a/src/interpreter/source-position-table.h
+++ b/src/interpreter/source-position-table.h
@@ -42,7 +42,7 @@ class SourcePositionTableBuilder : public PositionsRecorder {
 #ifdef ENABLE_SLOW_DCHECKS
         raw_entries_(zone),
 #endif
-        candidate_(kUninitializedCandidateOffset, 0, false) {
+        previous_() {
   }
 
   void AddStatementPosition(size_t bytecode_offset, int source_position);
@@ -60,7 +60,6 @@ class SourcePositionTableBuilder : public PositionsRecorder {
 #ifdef ENABLE_SLOW_DCHECKS
   ZoneVector<PositionTableEntry> raw_entries_;
 #endif
-  PositionTableEntry candidate_;  // Next entry to be written, if initialized.
   PositionTableEntry previous_;   // Previously written entry, to compute delta.
 };