[debugger] fix break locations for assignments and return.

src/parsing/pattern-rewriter.cc

Index: src/parsing/pattern-rewriter.cc
diff --git a/src/parsing/pattern-rewriter.cc b/src/parsing/pattern-rewriter.cc
index 97517747083e9831438996d5eeaa112cb8a07551..02d6de513fe9ce5ec8cd8f0895d4358af88a45ea 100644
--- a/src/parsing/pattern-rewriter.cc
+++ b/src/parsing/pattern-rewriter.cc
@@ -266,7 +266,7 @@ void Parser::PatternRewriter::VisitVariableProxy(VariableProxy* pattern) {
 
     if (initialize != NULL) {
       block_->statements()->Add(
-          factory()->NewExpressionStatement(initialize, RelocInfo::kNoPosition),
+          factory()->NewExpressionStatement(initialize, initialize->position()),
           zone());
     }
   } else if (value != nullptr && (descriptor_->mode == CONST_LEGACY ||
@@ -282,7 +282,8 @@ void Parser::PatternRewriter::VisitVariableProxy(VariableProxy* pattern) {
     DCHECK_NOT_NULL(proxy->var());
     DCHECK_NOT_NULL(value);
     // Add break location for destructured sub-pattern.
-    int pos = IsSubPattern() ? pattern->position() : RelocInfo::kNoPosition;
+    int pos =
+        IsSubPattern() ? pattern->position() : descriptor_->initialization_pos;
     Assignment* assignment =
         factory()->NewAssignment(Token::INIT, proxy, value, pos);
     block_->statements()->Add(
@@ -299,7 +300,8 @@ void Parser::PatternRewriter::VisitVariableProxy(VariableProxy* pattern) {
     // property).
     VariableProxy* proxy = initialization_scope->NewUnresolved(factory(), name);
     // Add break location for destructured sub-pattern.
-    int pos = IsSubPattern() ? pattern->position() : RelocInfo::kNoPosition;
+    int pos =
+        IsSubPattern() ? pattern->position() : descriptor_->initialization_pos;
     Assignment* assignment =
         factory()->NewAssignment(Token::INIT, proxy, value, pos);
     block_->statements()->Add(