Precise shift right result type derivation for all int32 input ranges.

src/compiler/typer.h

Index: src/compiler/typer.h
diff --git a/src/compiler/typer.h b/src/compiler/typer.h
index 4c04ddb973b3404b85a2522fc9c75003041d0b10..852522f658c79d5f6b5d7b93c13d385cbe1b2669 100644
--- a/src/compiler/typer.h
+++ b/src/compiler/typer.h
@@ -16,6 +16,15 @@ namespace compiler {
 class LazyTypeCache;
 
 
+struct IntType {
+  int32_t min;
+  int32_t max;
+  IntType(int32_t min, int32_t max) : min(min), max(max) {}
+};
+
+IntType JSShiftRightIntType(IntType lhs, IntType rhs);
+
+
 class Typer {
  public:
   Typer(Isolate* isolate, Graph* graph, MaybeHandle<Context> context);