[interpreter] Introduce fused bytecodes for common sequences.

test/cctest/interpreter/bytecode_expectations/ContextVariables.golden

 #
 # Autogenerated by generate-bytecode-expectations.
 #
 
 ---
 pool type: mixed
 execute: yes
 wrap: yes
 
 ---
@@ skipping 61 matching lines @@
 ]
 handlers: [
 ]
 
 ---
 snippet: "
   var a; (function() { a = 2; })(); return a;
 "
 frame size: 3
 parameter count: 1
-bytecode array length: 25
+bytecode array length: 24
 bytecodes: [
                 B(CallRuntime), U16(Runtime::kNewFunctionContext), R(closure), U8(1),
                 B(PushContext), R(0),
   /*   30 E> */ B(StackCheck),
-  /*   41 S> */ B(LdaUndefined),
-                B(Star), R(2),
+  /*   41 S> */ B(LdrUndefined), R(2),
                 B(CreateClosure), U8(0), U8(0),
                 B(Star), R(1),
   /*   64 E> */ B(Call), R(1), R(2), U8(1), U8(1),
   /*   68 S> */ B(LdaContextSlot), R(context), U8(4),
   /*   78 S> */ B(Return),
 ]
 constant pool: [
   InstanceType::SHARED_FUNCTION_INFO_TYPE,
 ]
 handlers: [
@@ skipping 288 matching lines @@
   var a245 = 0;
   var a246 = 0;
   var a247 = 0;
   var a248 = 0;
   eval();
   var b = 100;
   return b
 "
 frame size: 3
 parameter count: 1
-bytecode array length: 1046
+bytecode array length: 1044
 bytecodes: [
                 B(CallRuntime), U16(Runtime::kNewFunctionContext), R(closure), U8(1),
                 B(PushContext), R(0),
                 B(Ldar), R(this),
                 B(StaContextSlot), R(context), U8(4),
                 B(CreateUnmappedArguments),
                 B(StaContextSlot), R(context), U8(5),
                 B(Ldar), R(new_target),
                 B(StaContextSlot), R(context), U8(6),
   /*   30 E> */ B(StackCheck),
@@ skipping 488 matching lines @@
   /* 3365 S> */ B(LdaZero),
   /* 3365 E> */ B(StaContextSlot), R(context), U8(251),
   /* 3379 S> */ B(LdaZero),
   /* 3379 E> */ B(StaContextSlot), R(context), U8(252),
   /* 3393 S> */ B(LdaZero),
   /* 3393 E> */ B(StaContextSlot), R(context), U8(253),
   /* 3407 S> */ B(LdaZero),
   /* 3407 E> */ B(StaContextSlot), R(context), U8(254),
   /* 3421 S> */ B(LdaZero),
   /* 3421 E> */ B(StaContextSlot), R(context), U8(255),
-  /* 3424 S> */ B(LdaUndefined),
-                B(Star), R(2),
-  /* 3424 E> */ B(LdaGlobal), U8(0), U8(1),
-                B(Star), R(1),
+  /* 3424 S> */ B(LdrUndefined), R(2),
+  /* 3424 E> */ B(LdrGlobal), U8(0), U8(1), R(1),
   /* 3424 E> */ B(Call), R(1), R(2), U8(1), U8(0),
   /* 3440 S> */ B(LdaSmi), U8(100),
   /* 3440 E> */ B(Wide), B(StaContextSlot), R16(context), U16(256),
   /* 3445 S> */ B(Wide), B(LdaContextSlot), R16(context), U16(256),
   /* 3454 S> */ B(Return),
 ]
 constant pool: [
   InstanceType::ONE_BYTE_INTERNALIZED_STRING_TYPE,
 ]
 handlers: [
 ]