[interpreter] Fix source position of yield-exceptions in generators.

src/interpreter/bytecode-array-builder.cc

Index: src/interpreter/bytecode-array-builder.cc
diff --git a/src/interpreter/bytecode-array-builder.cc b/src/interpreter/bytecode-array-builder.cc
index 75bf631d300a9349e7369806592914800ebc3101..5069d5edc8449e1081bbafd373e7ddde65690ad5 100644
--- a/src/interpreter/bytecode-array-builder.cc
+++ b/src/interpreter/bytecode-array-builder.cc
@@ -760,7 +760,6 @@ BytecodeArrayBuilder& BytecodeArrayBuilder::ReThrow() {
 
 
 BytecodeArrayBuilder& BytecodeArrayBuilder::Return() {
-  SetReturnPosition();
   Output(Bytecode::kReturn);
   exit_seen_in_block_ = true;
   return *this;
@@ -864,6 +863,7 @@ void BytecodeArrayBuilder::LeaveBasicBlock() {
 void BytecodeArrayBuilder::EnsureReturn() {
   if (!exit_seen_in_block_) {
     LoadUndefined();
+    SetReturnPosition();
     Return();
   }
   DCHECK(exit_seen_in_block_);