Source maps: Fix missing debug info in nested blocks (#6525)

The special block nesting logic also needs to handle emitting debug info.

Author: vouillon

src/wasm-stack.h

@@ -328,6 +328,7 @@ void BinaryenIRWriter<SubType>::visitBlock(Block* curr) {
       parents.push_back(curr);
       emit(curr);
       curr = child;
+      emitDebugLocation(curr);
     }
     // Emit the current block, which does not have a block as a child in the
     // first position.

test/lit/source-map.wast

@@ -32,6 +32,18 @@
     )
     ;;@ src.cpp:90:1
   )
+
+  (func $nested-blocks
+    ;;@ src.cpp:2:1
+    (block $label$1
+      ;;@ src.cpp:2:2
+      (block $label$2
+        (br $label$2)
+      )
+    )
+    ;;@ src.cpp:3:1
+    (return)
+  )
 )
 
 ;; CHECK:       ;;@ src.cpp:0:1
@@ -59,3 +71,15 @@
 ;; CHECK-NEXT:   )
 ;; CHECK-NEXT:   ;;@ src.cpp:90:1
 ;; CHECK-NEXT:  )
+
+;; CHECK:      (func $nested-blocks
+;; CHECK-NEXT:  ;;@ src.cpp:2:1
+;; CHECK-NEXT:  (block $label$1
+;; CHECK-NEXT:   ;;@ src.cpp:2:2
+;; CHECK-NEXT:   (block $label$2
+;; CHECK-NEXT:    (br $label$2)
+;; CHECK-NEXT:   )
+;; CHECK-NEXT:  )
+;; CHECK-NEXT:  ;;@ src.cpp:3:1
+;; CHECK-NEXT:  (return)
+;; CHECK-NEXT: )