MIPS: Force context allocation for variables in generator scopes.

Port r14152 (4e58a8ea)

Original commit message:
* src/scopes.h (ForceContextAllocation, has_forced_context_allocation):
  New interface to force context allocation for an entire function's
  scope.

* src/scopes.cc: Unless a new scope is a function scope, if its outer
  scope has forced context allocation, it should also force context
  allocation.
  (MustAllocateInContext): Return true if the scope as a whole has
  forced context allocation.
  (CollectStackAndContextLocals): Allow temporaries to be
  context-allocated.

* src/parser.cc (ParseFunctionLiteral): Force context allocation for
  generator scopes.

* src/v8globals.h (VariableMode): Update comment on TEMPORARY.

* src/arm/full-codegen-arm.cc (Generate):
* src/ia32/full-codegen-ia32.cc (Generate):
* src/x64/full-codegen-x64.cc (Generate): Assert that generators have no
  stack slots.

    * test/mjsunit/harmony/generators-instantiation.js: New test.

BUG=

Review URL: https://codereview.chromium.org/13726009

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14157 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/full-codegen-mips.cc

@@ -170,8 +170,6 @@ void FullCodeGenerator::Generate() {
   // the frame (that is done below).
   FrameScope frame_scope(masm_, StackFrame::MANUAL);
 
-  int locals_count = info->scope()->num_stack_slots();
-
   info->set_prologue_offset(masm_->pc_offset());
   // The following three instructions must remain together and unmodified for
   // code aging to work properly.
@@ -183,6 +181,9 @@ void FullCodeGenerator::Generate() {
   __ Addu(fp, sp, Operand(2 * kPointerSize));
 
   { Comment cmnt(masm_, "[ Allocate locals");
+    int locals_count = info->scope()->num_stack_slots();
+    // Generators allocate locals, if any, in context slots.
+    ASSERT(!info->function()->is_generator() || locals_count == 0);
     for (int i = 0; i < locals_count; i++) {
       __ push(at);
     }