Do not attempt to create implicit vars in the global scope.

Fixes a rare stack overflow error.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=189643811

src/com/google/javascript/jscomp/TypedScope.java

@@ -141,6 +141,11 @@ TypedVar declare(String name, Node nameNode,
 
   @Override
   TypedVar makeImplicitVar(ImplicitVar var) {
+    if (this.isGlobal()) {
+      // TODO(sdh): This is incorrect for 'global this', but since that's currently not handled
+      // by this code, it's okay to bail out now until we find the root cause.  See b/74980936.
+      return null;
+    }
     return new TypedVar(false, var.name, null, getImplicitVarType(var), this, -1, null);
   }
 

test/com/google/javascript/jscomp/TypedScopeCreatorTest.java

@@ -2091,6 +2091,29 @@ public void testGenerator2() {
     assertEquals("Generator<?>", findNameType("g", globalScope).toString());
   }
 
+  // Just check that this doesn't cause a StackOverflowError.
+  public void testArgumentsStackOverflow() {
+    String js = lines(
+        "/**",
+        " * @fileoverview",
+        " * @suppress {es5Strict}",
+        " */",
+        "",
+        "function getStackTrace() {",
+        "  try {",
+        "    throw new Error();",
+        "  } catch (e) {",
+        "    return 0;",
+        "  }",
+        "",
+        "  if (typeof (arguments.caller) != 'undefined') {}",
+        "",
+        "  return '';",
+        "}",
+        "");
+    testSame(js);
+  }
+
   public void testMemoization() throws Exception {
     Node root1 = createEmptyRoot();
     Node root2 = createEmptyRoot();