[compiler] Introduce code stubs for string relational comparisons.

src/compiler/linkage.cc

Index: src/compiler/linkage.cc
diff --git a/src/compiler/linkage.cc b/src/compiler/linkage.cc
index a0a8945488781c6c977216ce73b88422395a1438..9d64cebbf7da9c9025a03f815b8ad7eda25bb238 100644
--- a/src/compiler/linkage.cc
+++ b/src/compiler/linkage.cc
@@ -161,6 +161,11 @@ int Linkage::FrameStateInputCount(Runtime::FunctionId function) {
     case Runtime::kReThrow:
     case Runtime::kStringCompare:
     case Runtime::kStringEqual:
+    case Runtime::kStringNotEqual:
+    case Runtime::kStringLessThan:
+    case Runtime::kStringLessThanOrEqual:
+    case Runtime::kStringGreaterThan:
+    case Runtime::kStringGreaterThanOrEqual:
     case Runtime::kToFastProperties:  // TODO(jarin): Is it safe?
     case Runtime::kTraceEnter:
     case Runtime::kTraceExit: