Fix unaligned accesses in back_edge tables.

src/full-codegen.h

Index: src/full-codegen.h
diff --git a/src/full-codegen.h b/src/full-codegen.h
index 7e6450655f5258eac705877575c7a399954ab580..a9db54e32c18284b17f510d3384c55abebeab0f3 100644
--- a/src/full-codegen.h
+++ b/src/full-codegen.h
@@ -136,7 +136,7 @@ class FullCodeGenerator: public AstVisitor {
 #error Unsupported target architecture.
 #endif
 
-  static const int kBackEdgeEntrySize = 2 * kIntSize + kOneByteSize;
+  static const int kBackEdgeEntrySize = 3 * kIntSize;
 
  private:
   class Breakable;
@@ -648,7 +648,7 @@ class FullCodeGenerator: public AstVisitor {
   struct BackEdgeEntry {
     BailoutId id;
     unsigned pc;
-    uint8_t loop_depth;
+    uint32_t loop_depth;
   };
 
   struct TypeFeedbackCellEntry {