[interpreter] Make JumpLoop kill its block

Add JumpLoop to the list of bytecodes that unconditionally exit a
block, so that bytecodes are not emitted after a JumpLoop until there's
a bound label.

As a drive by, fix the bytecode random iterator's initialisation to use
'done()' directly (the old condition worked for Return, but was failing
for wide JumpLoops that ended the bytecode).

Change-Id: I63910602efbac8ad2b995a8fe6559a9f8f4b83b9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3419919
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78806}

src/interpreter/bytecode-array-random-iterator.cc

@@ -20,7 +20,7 @@ BytecodeArrayRandomIterator::BytecodeArrayRandomIterator(
 void BytecodeArrayRandomIterator::Initialize() {
   // Run forwards through the bytecode array to determine the offset of each
   // bytecode.
-  while (current_offset() < bytecode_array()->length()) {
+  while (!done()) {
     offsets_.push_back(current_offset());
     Advance();
   }

src/interpreter/bytecode-array-writer.cc

@@ -238,6 +238,7 @@ void BytecodeArrayWriter::UpdateExitSeenInBlock(Bytecode bytecode) {
     case Bytecode::kReThrow:
     case Bytecode::kAbort:
     case Bytecode::kJump:
+    case Bytecode::kJumpLoop:
     case Bytecode::kJumpConstant:
     case Bytecode::kSuspendGenerator:
       exit_seen_in_block_ = true;