[Interpreter] Replace BytecodeRegisterAllocator with a simple bump pointer.

test/cctest/interpreter/bytecode_expectations/UnaryOperators.golden

 #
 # Autogenerated by generate-bytecode-expectations.
 #
 
 ---
 execute: yes
 wrap: yes
 
 ---
 snippet: "
@@ skipping 77 matching lines @@
 ]
 handlers: [
 ]
 
 ---
 snippet: "
   var x = 1234;
   var y = void (x * x - 1);
   return y;
 "
-frame size: 4
+frame size: 3
 parameter count: 1
 bytecode array length: 23
 bytecodes: [
   /*   30 E> */ B(StackCheck),
   /*   42 S> */ B(Wide), B(LdaSmi), U16(1234),
                 B(Star), R(0),
   /*   56 S> */ B(Nop),
   /*   66 E> */ B(Mul), R(0), U8(2),
-                B(Star), R(3),
-                B(SubSmi), U8(1), R(3), U8(3),
+                B(Star), R(2),
+                B(SubSmi), U8(1), R(2), U8(3),
                 B(LdrUndefined), R(1),
                 B(Ldar), R(1),
   /*   74 S> */ B(Nop),
   /*   84 S> */ B(Return),
 ]
 constant pool: [
 ]
 handlers: [
 ]
 
@@ skipping 53 matching lines @@
                 B(Star), R(0),
   /*   46 S> */ B(LdaSmi), U8(-1),
                 B(Mul), R(0), U8(2),
   /*   57 S> */ B(Return),
 ]
 constant pool: [
 ]
 handlers: [
 ]