[date] Properly handle timezones with non-ASCII characters.

The timezone part of the Date string representation might contain
non-ASCII characters depending on the exact platform configuration,
so we cannot safely assume that the whole date string is ASCII
encoded.

CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel
R=yangguo@chromium.org
BUG=chromium:581925
LOG=n

Review URL: https://codereview.chromium.org/1838063002

Cr-Commit-Position: refs/heads/master@{#35089}

src/builtins.cc

@@ -2750,7 +2750,11 @@ BUILTIN(DateConstructor) {
   char buffer[128];
   Vector<char> str(buffer, arraysize(buffer));
   ToDateString(time_val, str, isolate->date_cache());
-  return *isolate->factory()->NewStringFromAsciiChecked(str.start());
+  Handle<String> result;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, result,
+      isolate->factory()->NewStringFromUtf8(CStrVector(buffer)));
+  return *result;
 }
 
 
@@ -3330,7 +3334,11 @@ BUILTIN(DatePrototypeToDateString) {
   char buffer[128];
   Vector<char> str(buffer, arraysize(buffer));
   ToDateString(date->value()->Number(), str, isolate->date_cache(), kDateOnly);
-  return *isolate->factory()->NewStringFromAsciiChecked(str.start());
+  Handle<String> result;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, result,
+      isolate->factory()->NewStringFromUtf8(CStrVector(buffer)));
+  return *result;
 }
 
 
@@ -3370,7 +3378,11 @@ BUILTIN(DatePrototypeToString) {
   char buffer[128];
   Vector<char> str(buffer, arraysize(buffer));
   ToDateString(date->value()->Number(), str, isolate->date_cache());
-  return *isolate->factory()->NewStringFromAsciiChecked(str.start());
+  Handle<String> result;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, result,
+      isolate->factory()->NewStringFromUtf8(CStrVector(buffer)));
+  return *result;
 }
 
 
@@ -3381,7 +3393,11 @@ BUILTIN(DatePrototypeToTimeString) {
   char buffer[128];
   Vector<char> str(buffer, arraysize(buffer));
   ToDateString(date->value()->Number(), str, isolate->date_cache(), kTimeOnly);
-  return *isolate->factory()->NewStringFromAsciiChecked(str.start());
+  Handle<String> result;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, result,
+      isolate->factory()->NewStringFromUtf8(CStrVector(buffer)));
+  return *result;
 }