[turbofan] Assign types to remaining builtins on String.prototype.

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index ac455235d82abc00516fa19a6fcf73b9c17532b4..c2aa1879ddf9e4efe9acf7153f17f14c3536bf8b 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -1369,6 +1369,7 @@ Type* Typer::Visitor::JSCallFunctionTyper(Type* fun, Typer* t) {
           return t->cache_.kJSDateSecondType;
         case kDateGetTime:
           return t->cache_.kJSDateValueType;
+
         // Number functions.
         case kNumberIsFinite:
         case kNumberIsInteger:
@@ -1381,16 +1382,41 @@ Type* Typer::Visitor::JSCallFunctionTyper(Type* fun, Typer* t) {
           return t->cache_.kIntegerOrMinusZeroOrNaN;
         case kNumberToString:
           return Type::String();
+
         // String functions.
         case kStringCharCodeAt:
           return Type::Union(Type::Range(0, kMaxUInt16, t->zone()), Type::NaN(),
                              t->zone());
         case kStringCharAt:
+          return Type::String();
+        case kStringCodePointAt:
+          return Type::Union(Type::Range(0.0, String::kMaxCodePoint, t->zone()),
+                             Type::Undefined(), t->zone());
         case kStringConcat:
         case kStringFromCharCode:
+        case kStringFromCodePoint:
+          return Type::String();
+        case kStringIndexOf:
+        case kStringLastIndexOf:
+          return Type::Range(-1.0, String::kMaxLength - 1.0, t->zone());
+        case kStringEndsWith:
+        case kStringIncludes:
+          return Type::Boolean();
+        case kStringRaw:
+        case kStringRepeat:
+        case kStringSlice:
+          return Type::String();
+        case kStringStartsWith:
+          return Type::Boolean();
         case kStringSubstr:
+        case kStringSubstring:
         case kStringToLowerCase:
+        case kStringToString:
         case kStringToUpperCase:
+        case kStringTrim:
+        case kStringTrimLeft:
+        case kStringTrimRight:
+        case kStringValueOf:
           return Type::String();
 
         case kStringIterator: