Improve positions tracking inside the HGraphBuilder.

src/flag-definitions.h

Index: src/flag-definitions.h
diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index 9c88086275d7e1235044708e67460d0fbf5f942a..6e4e2363ade27d00d1014cb87ff72f9d4191610e 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -822,6 +822,9 @@ DEFINE_bool(redirect_code_traces, false,
 DEFINE_string(redirect_code_traces_to, NULL,
             "output deopt information and disassembly into the given file")
 
+DEFINE_bool(hydrogen_track_positions, false,
+            "track source code positions when building IR")
+
 //
 // Disassembler only flags
 //
@@ -854,8 +857,6 @@ DEFINE_bool(print_unopt_code, false, "print unoptimized code before "
             "printing optimized code based on it")
 DEFINE_bool(print_code_verbose, false, "print more information for code")
 DEFINE_bool(print_builtin_code, false, "print generated code for builtins")
-DEFINE_bool(emit_opt_code_positions, false,
-            "annotate optimize code with source code positions")
 
 #ifdef ENABLE_DISASSEMBLER
 DEFINE_bool(sodium, false, "print generated code output suitable for use with "
@@ -864,7 +865,7 @@ DEFINE_bool(sodium, false, "print generated code output suitable for use with "
 DEFINE_implication(sodium, print_code_stubs)
 DEFINE_implication(sodium, print_code)
 DEFINE_implication(sodium, print_opt_code)
-DEFINE_implication(sodium, emit_opt_code_positions)
+DEFINE_implication(sodium, hydrogen_track_positions)
 DEFINE_implication(sodium, code_comments)
 
 DEFINE_bool(print_all_code, false, "enable all flags related to printing code")