In generators, "yield" cannot be an arrow formal parameter name

Thanks to André Bargull for the report.

BUG=v8:4212
LOG=N
R=rossberg@chromium.org

Review URL: https://codereview.chromium.org/1309523005

Cr-Commit-Position: refs/heads/master@{#30381}

src/preparser.h

@@ -2934,6 +2934,7 @@ ParserBase<Traits>::ParseYieldExpression(ExpressionClassifier* classifier,
   // YieldExpression ::
   //   'yield' ([no line terminator] '*'? AssignmentExpression)?
   int pos = peek_position();
+  BindingPatternUnexpectedToken(classifier);
   Expect(Token::YIELD, CHECK_OK);
   ExpressionT generator_object =
       factory()->NewVariableProxy(function_state_->generator_object_variable());

test/cctest/test-parsing.cc

@@ -3801,6 +3801,50 @@ TEST(ArrowFunctionsSloppyParameterNames) {
 }
 
 
+TEST(ArrowFunctionsYieldParameterNameInGenerator) {
+  const char* sloppy_function_context_data[][2] = {
+    {"(function f() { (", "); });"},
+    {NULL, NULL}
+  };
+
+  const char* strict_function_context_data[][2] = {
+    {"(function f() {'use strong'; (", "); });"},
+    {"(function f() {'use strict'; (", "); });"},
+    {NULL, NULL}
+  };
+
+  const char* generator_context_data[][2] = {
+    {"(function *g() {'use strong'; (", "); });"},
+    {"(function *g() {'use strict'; (", "); });"},
+    {"(function *g() { (", "); });"},
+    {NULL, NULL}
+  };
+
+  const char* arrow_data[] = {
+    "yield => {}",
+    "(yield) => {}",
+    "(a, yield) => {}",
+    "(yield, a) => {}",
+    "(yield, ...a) => {}",
+    "(a, ...yield) => {}",
+    "({yield}) => {}",
+    "([yield]) => {}",
+    NULL
+  };
+
+  static const ParserFlag always_flags[] = { kAllowHarmonyDestructuring,
+                                             kAllowHarmonyRestParameters,
+                                             kAllowHarmonyArrowFunctions,
+                                             kAllowStrongMode};
+  RunParserSyncTest(sloppy_function_context_data, arrow_data, kSuccess, NULL, 0,
+                    always_flags, arraysize(always_flags));
+  RunParserSyncTest(strict_function_context_data, arrow_data, kError, NULL, 0,
+                    always_flags, arraysize(always_flags));
+  RunParserSyncTest(generator_context_data, arrow_data, kError, NULL, 0,
+                    always_flags, arraysize(always_flags));
+}
+
+
 TEST(SuperNoErrors) {
   // Tests that parser and preparser accept 'super' keyword in right places.
   const char* context_data[][2] = {