[interpreter] Introduce fused bytecodes for common sequences.

test/cctest/interpreter/bytecode_expectations/DeclareGlobals.golden

 #
 # Autogenerated by generate-bytecode-expectations.
 #
 
 ---
 pool type: mixed
 execute: no
 wrap: no
 top level: yes
 
@@ skipping 85 matching lines @@
 handlers: [
 ]
 
 ---
 snippet: "
   function f() {}
   f();
 "
 frame size: 3
 parameter count: 1
-bytecode array length: 29
+bytecode array length: 27
 bytecodes: [
                 B(LdaConstant), U8(0),
                 B(Star), R(1),
                 B(LdaZero),
                 B(Star), R(2),
                 B(CallRuntime), U16(Runtime::kDeclareGlobals), R(1), U8(2),
   /*    0 E> */ B(StackCheck),
-  /*   16 S> */ B(LdaUndefined),
-                B(Star), R(2),
-                B(LdaGlobal), U8(1), U8(1),
-                B(Star), R(1),
+  /*   16 S> */ B(LdrUndefined), R(2),
+                B(LdrGlobal), U8(1), U8(1), R(1),
   /*   16 E> */ B(Call), R(1), R(2), U8(1), U8(3),
                 B(Star), R(0),
   /*   20 S> */ B(Return),
 ]
 constant pool: [
   InstanceType::FIXED_ARRAY_TYPE,
   InstanceType::ONE_BYTE_INTERNALIZED_STRING_TYPE,
 ]
 handlers: [
 ]