First two codegen tests passing on SIMMIPS

runtime/vm/assembler_mips.h

Index: runtime/vm/assembler_mips.h
===================================================================
--- runtime/vm/assembler_mips.h	(revision 20729)
+++ runtime/vm/assembler_mips.h	(working copy)
@@ -162,18 +162,10 @@
     buffer_.FinalizeInstructions(region);
   }
 
-  // Set up a Dart frame on entry with a frame pointer and PC information to
-  // enable easy access to the RawInstruction object of code corresponding
-  // to this frame.
-  void EnterDartFrame(intptr_t frame_size) {
-    UNIMPLEMENTED();
-  }
-
   // Set up a stub frame so that the stack traversal code can easily identify
   // a stub frame.
-  void EnterStubFrame() {
-    UNIMPLEMENTED();
-  }
+  void EnterStubFrame();
+  void LeaveStubFrame();
 
   // Instruction pattern from entrypoint is used in dart frame prologs
   // to set up the frame and save a PC which can be used to figure out the
@@ -250,6 +242,12 @@
     beq(R0, R0, l);
   }
 
+  void bal(Label *l) {
+    ASSERT(!in_delay_slot_);
+    EmitRegImmBranch(BGEZAL, R0, l);
+    EmitBranchDelayNop();
+  }
+
   // Branch if equal.
   void beq(Register rs, Register rt, Label* l) {
     ASSERT(!in_delay_slot_);
@@ -546,6 +544,18 @@
     jr(TMP);
   }
 
+  // If the signed value in rs is less than value, rd is 1, and 0 otherwise.
+  void LessThanSImmediate(Register rd, Register rs, int32_t value) {
+    LoadImmediate(TMP, value);
+    slt(rd, rs, TMP);
+  }
+
+  // If the unsigned value in rs is less than value, rd is 1, and 0 otherwise.
+  void LessThanUImmediate(Register rd, Register rs, uint32_t value) {
+    LoadImmediate(TMP, value);
+    sltu(rd, rs, TMP);
+  }
+
   void Drop(intptr_t stack_elements) {
     ASSERT(stack_elements >= 0);
     if (stack_elements > 0) {
@@ -578,6 +588,14 @@
     jr(RA);
   }
 
+  void SmiTag(Register reg) {
+    sll(reg, reg, kSmiTagSize);
+  }
+
+  void SmiUntag(Register reg) {
+    sra(reg, reg, kSmiTagSize);
+  }
+
   void LoadWordFromPoolOffset(Register rd, int32_t offset);
   void LoadObject(Register rd, const Object& object);
   void PushObject(const Object& object);
@@ -586,6 +604,12 @@
   // set to non-zero otherwise.
   void CompareObject(Register rd, Register rn, const Object& object);
 
+  // Set up a Dart frame on entry with a frame pointer and PC information to
+  // enable easy access to the RawInstruction object of code corresponding
+  // to this frame.
+  void EnterDartFrame(intptr_t frame_size);
+  void LeaveDartFrame();
+
  private:
   AssemblerBuffer buffer_;
   GrowableObjectArray& object_pool_;  // Objects and patchable jump targets.